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  • getelementbyid does not work in firefox

    - by gaurab
    hi, this below mentioned code works perfect in internet explorer but not in firefox... i get an error in line in firefox: document.getElementById("supplier_no").value= values_array[0]; that getElementById returns null. how to solve the problem? var winName; //variable for the popup window var g_return_destination = null ; //variable to track where the data gets sent back to. // Set the value in the original pages text box. function f_set_home_value( as_Value ) { if (document.getElementById(g_return_destination[0]).name == "netbank_supplier_name_info" ) { //clear the old values for (selnum = 1; selnum <= 5; selnum++) { document.getElementById("expense_account"+selnum).value = ""; document.getElementById("expense_account_name"+selnum).value = ""; document.getElementById("expense_vat_flag"+selnum).value = "off"; document.getElementById("expense_vat_flag"+selnum).checked = ""; document.getElementById("expense_vat_amount"+selnum).value = ""; document.getElementById("expense_vat_code"+selnum).value = ""; document.getElementById("expense_period"+selnum).value = ""; document.getElementById("expense_date"+selnum).value = ""; if (selnum!=1) {//these are sometimes defaulted in, and in any case you will always have line1 document.getElementById("expense_more_dept"+selnum).value = ""; document.getElementById("expense_more_prj"+selnum).value = ""; document.getElementById("expense_more_subj"+selnum).value = ""; } document.getElementById("expense_amount"+selnum).value = ""; } var values_array = as_Value[0].split("!"); document.getElementById("supplier_no").value= values_array[0]; document.getElementById("supplier_bankAccount_no").value= values_array[1]; str = values_array[2] ; str = str.split(";sp;").join(" "); document.getElementById("default_expense_account").value= str; document.getElementById("expense_account1").value= str; document.getElementById("expense_more_sok1").disabled= false; str = values_array[3] ; str = str.split(";sp;").join(" "); document.getElementById("payment_term").value= str; strPeriod = calcPeriod(str,document.getElementById("due_date").value); document.getElementById("expense_period1").value = (strPeriod); strExpenseDate = calcExpenseDate(str,document.getElementById("due_date").value); document.getElementById("expense_date1").value = (strExpenseDate); str = values_array[4] ; str = str.split(";sp;").join(" "); document.getElementById("expense_account_name1").value= str; str = values_array[5] ; str = str.split(";sp;").join(" "); document.getElementById("expense_vat_code1").value= str; if (str == 0) { document.getElementById("expense_vat_flag1").checked= ''; document.getElementById("expense_vat_flag1").disabled= true; }else{ document.getElementById("expense_vat_flag1").checked= 'yes'; document.getElementById("expense_vat_flag1").value= 'on'; document.getElementById("expense_vat_flag1").disabled= false; } str = values_array[6] ; str = str.split(";sp;").join(" "); document.getElementById("supplier_name").value= str; var str = values_array[7]; str = str.split(";sp;").join(" "); str = str.split("&cr;").join("\r"); document.getElementById("netbank_supplier_name_info").value= str; strx = justNumberNF(document.getElementById("amount").value); document.all["expense_vat_amount1"].value = NetbankToDollarsAndCents(strx * (24/124)) ; document.getElementById("amount").value=NetbankToDollarsAndCents(strx); document.getElementById("expense_amount1").value = document.getElementById("amount").value; document.getElementById("expense_amount2").value = ''; document.getElementById("expense_account2").value= ''; //document.getElementById("expense_vat_flag2").value= ''; document.getElementById("expense_vat_amount2").value= ''; document.getElementById("expense_amount3").value = ''; document.getElementById("expense_account3").value= ''; //.getElementById("expense_vat_flag3").value= ''; document.getElementById("expense_vat_amount3").value= ''; document.getElementById("expense_amount4").value = ''; document.getElementById("expense_account4").value= ''; //document.getElementById("expense_vat_flag4").value= ''; document.getElementById("expense_vat_amount4").value= ''; document.getElementById("expense_amount5").value = ''; document.getElementById("expense_account5").value= ''; //document.getElementById("expense_vat_flag5").value= ''; document.getElementById("expense_vat_amount5").value= ''; str = values_array[8] ; str = str.split(";sp;").join(" "); if (str=="2"){ document.frmName.ButtonSelPeriodisering1.disabled=false; document.frmName.ButtonSelPeriodisering1.click(); } winName.close(); } } //Pass Data Back to original window function f_popup_return(as_Value) { var l_return = new Array(1); l_return[0] = as_Value; f_set_home_value(l_return); } function justNumberNF(val){ val = (val==null) ? 0 : val; // check if a number, otherwise try taking out non-number characters. if (isNaN(val)) { var newVal = parseFloat(val.replace(/[^\d\.\-]/g, '.')); // check if still not a number. Might be undefined, '', etc., so just replace with 0. return (isNaN(newVal) ? 0 : newVal); } // return 0 in place of infinite numbers. else if (!isFinite(val)) { return 0; } return val; }; function NetbankToDollarsAndCents(n) { var s = "" + Math.round(n * 100) / 100 ; var i = s.indexOf('.') ; if (i < 0) {return s + ",00" } ; var t = s.substring(0, i + 1) + s.substring(i + 1, i + 3) ; if (i + 2 == s.length) {t += "0"} ; return t.replace('.',',') ; }

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  • crash in calloc

    - by mmd
    I'm trying to debug a program I wrote. I ran it inside gdb and I managed to catch a SIGABRT from inside calloc(). I'm completely confused about how this can arise. Can it be a bug in gcc or even libc?? More details: My program uses OpenMP. I ran it through valgrind in single-threaded mode with no errors. I also use mmap() to load a 40GB file, but I doubt that is relevant. Inside gdb, I'm running with 30 threads. Several identical runs (same input&CL) finished correctly, until the problematic one that I caught. On the surface this suggests there might be a race condition of some type. However, the SIGABRT comes from calloc() which is out of my control. Here is some relevant gdb output: (gdb) info threads [...] * 11 Thread 0x7ffff0056700 (LWP 73449) 0x00007ffff6a948a5 in raise () from /lib64/libc.so.6 [...] (gdb) thread 11 [Switching to thread 11 (Thread 0x7ffff0056700 (LWP 73449))]#0 0x00007ffff6a948a5 in raise () from /lib64/libc.so.6 (gdb) bt #0 0x00007ffff6a948a5 in raise () from /lib64/libc.so.6 #1 0x00007ffff6a96085 in abort () from /lib64/libc.so.6 #2 0x00007ffff6ad1fe7 in __libc_message () from /lib64/libc.so.6 #3 0x00007ffff6ad7916 in malloc_printerr () from /lib64/libc.so.6 #4 0x00007ffff6adb79f in _int_malloc () from /lib64/libc.so.6 #5 0x00007ffff6adbdd6 in calloc () from /lib64/libc.so.6 #6 0x000000000040e87f in my_calloc (re=0x7fff2867ef10, st=0, options=0x632020) at gmapper/../gmapper/../common/my-alloc.h:286 #7 read_get_hit_list_per_strand (re=0x7fff2867ef10, st=0, options=0x632020) at gmapper/mapping.c:1046 #8 0x000000000041308a in read_get_hit_list (re=<value optimized out>, options=0x632010, n_options=1) at gmapper/mapping.c:1239 #9 handle_read (re=<value optimized out>, options=0x632010, n_options=1) at gmapper/mapping.c:1806 #10 0x0000000000404f35 in launch_scan_threads (.omp_data_i=<value optimized out>) at gmapper/gmapper.c:557 #11 0x00007ffff7230502 in ?? () from /usr/lib64/libgomp.so.1 #12 0x00007ffff6dfc851 in start_thread () from /lib64/libpthread.so.0 #13 0x00007ffff6b4a11d in clone () from /lib64/libc.so.6 (gdb) f 6 #6 0x000000000040e87f in my_calloc (re=0x7fff2867ef10, st=0, options=0x632020) at gmapper/../gmapper/../common/my-alloc.h:286 286 res = calloc(size, 1); (gdb) p size $2 = 814080 (gdb) The function my_calloc() is just a wrapper, but the problem is not in there, as the real calloc() call looks legit. These are the limits set in the shell: $ ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 2067285 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 10240 cpu time (seconds, -t) unlimited max user processes (-u) 1024 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited The program is not out of memory, it's using 41GB on a machine with 256GB available: $ top -b -n 1 | grep gmapper 73437 user 20 0 41.5g 16g 15g T 0.0 6.6 55:17.24 gmapper-ls $ free -m total used free shared buffers cached Mem: 258437 195567 62869 0 82 189677 -/+ buffers/cache: 5807 252629 Swap: 0 0 0 I compiled using gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4), with flags -g -O2 -DNDEBUG -mmmx -msse -msse2 -fopenmp -Wall -Wno-deprecated -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS.

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  • Speed Problem with Wireless Connectivity on Cisco 877w

    - by Carl Crawley
    Having a bit of a weird one with my local LAN setup. I recently installed a Cisco 877W router on my DSL2+ connection and all is working really well.. Upgraded the IOS to 12.4 and my wired clients are streaming connectivity superfast at 1.3mb/s. However, there seems to be an issue with my wireless clients - I can't seem to stream any data across the local wireless connection (LAN) and using the Internet, whilst responsive enough isn't really comparable with the wired connection speed. For example, all devices are connected to an 8 Port Gb switch on FE0 from the Router with a NAS disk and on my wired clients, I can transfer/stream etc absolutely fine - however, transferring a local 700Mb file on my local LAN estimates 7-8 hours to transfer :( The Wireless config is as follows : interface Dot11Radio0 description WIRELESS INTERFACE no ip address ! encryption mode ciphers tkip ! ssid [MySSID] ! speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 channel 2462 station-role root rts threshold 2312 world-mode dot11d country GB indoor bridge-group 1 bridge-group 1 subscriber-loop-control bridge-group 1 spanning-disabled bridge-group 1 block-unknown-source no bridge-group 1 source-learning no bridge-group 1 unicast-flooding All devices are connected to the Gb Switch which is connected to FE0 with the following: Hardware is Fast Ethernet, address is 0021.a03e.6519 (bia 0021.a03e.6519) Description: Uplink to Switch MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full-duplex, 100Mb/s ARP type: ARPA, ARP Timeout 04:00:00 Last input never, output never, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 14000 bits/sec, 19 packets/sec 5 minute output rate 167000 bits/sec, 23 packets/sec 177365 packets input, 52089562 bytes, 0 no buffer Received 919 broadcasts, 0 runts, 0 giants, 0 throttles 260 input errors, 260 CRC, 0 frame, 0 overrun, 0 ignored 0 input packets with dribble condition detected 156673 packets output, 106218222 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out Not sure why I'm having problems on the wireless and I've reached the end of my Cisco knowledge... Thanks for any pointers! Carl

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  • Using getters/setters in Java

    - by Crystal
    I'm having some trouble with the idea of accessing variables from other classes. I had a post here: http://stackoverflow.com/questions/3011642/having-access-to-a-private-variable-from-other-classes-in-java where I got some useful information, and thought an example would be better show it, and ask a separate question as well. I have a form that I can input data to, and it has a List variable. I didn't make it static at first, but I thought if I needed to get the total size from another class, then I wouldn't create an instance of that class in order to use the function to getTotalContacts. I basically want to update my status bar with the total number of contacts that are in my list. One of the members said in the above post to use the original Foo member to get the contacts, but I'm not sure how that works in this case. Any thoughts would be appreciated. Thanks. import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.util.List; import java.util.ArrayList; public class AddressBook { public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { AddressBookFrame frame = new AddressBookFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JMenuBar menuBar = new JMenuBar(); frame.setJMenuBar(menuBar); JMenu fileMenu = new JMenu("File"); JMenuItem openItem = new JMenuItem("Open"); JMenuItem saveItem = new JMenuItem("Save"); JMenuItem saveAsItem = new JMenuItem("Save As"); JMenuItem printItem = new JMenuItem("Print"); JMenuItem exitItem = new JMenuItem("Exit"); fileMenu.add(openItem); fileMenu.add(saveItem); fileMenu.add(saveAsItem); fileMenu.add(printItem); fileMenu.add(exitItem); menuBar.add(fileMenu); JMenu editMenu = new JMenu("Edit"); JMenuItem newItem = new JMenuItem("New"); JMenuItem editItem = new JMenuItem("Edit"); JMenuItem deleteItem = new JMenuItem("Delete"); JMenuItem findItem = new JMenuItem("Find"); JMenuItem firstItem = new JMenuItem("First"); JMenuItem previousItem = new JMenuItem("Previous"); JMenuItem nextItem = new JMenuItem("Next"); JMenuItem lastItem = new JMenuItem("Last"); editMenu.add(newItem); editMenu.add(editItem); editMenu.add(deleteItem); editMenu.add(findItem); editMenu.add(firstItem); editMenu.add(previousItem); editMenu.add(nextItem); editMenu.add(lastItem); menuBar.add(editMenu); JMenu helpMenu = new JMenu("Help"); JMenuItem documentationItem = new JMenuItem("Documentation"); JMenuItem aboutItem = new JMenuItem("About"); helpMenu.add(documentationItem); helpMenu.add(aboutItem); menuBar.add(helpMenu); frame.setVisible(true); } }); } } class AddressBookFrame extends JFrame { public AddressBookFrame() { setLayout(new BorderLayout()); setTitle("Address Book"); setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT); AddressBookToolBar toolBar = new AddressBookToolBar(); add(toolBar, BorderLayout.NORTH); AddressBookStatusBar aStatusBar = new AddressBookStatusBar(); add(aStatusBar, BorderLayout.SOUTH); AddressBookForm form = new AddressBookForm(); add(form, BorderLayout.CENTER); } public static final int DEFAULT_WIDTH = 500; public static final int DEFAULT_HEIGHT = 500; } /* Create toolbar buttons and add buttons to toolbar */ class AddressBookToolBar extends JPanel { public AddressBookToolBar() { setLayout(new FlowLayout(FlowLayout.LEFT)); JToolBar bar = new JToolBar(); JButton newButton = new JButton("New"); JButton editButton = new JButton("Edit"); JButton deleteButton = new JButton("Delete"); JButton findButton = new JButton("Find"); JButton firstButton = new JButton("First"); JButton previousButton = new JButton("Previous"); JButton nextButton = new JButton("Next"); JButton lastButton = new JButton("Last"); bar.add(newButton); bar.add(editButton); bar.add(deleteButton); bar.add(findButton); bar.add(firstButton); bar.add(previousButton); bar.add(nextButton); bar.add(lastButton); add(bar); } } /* Creates the status bar string */ class AddressBookStatusBar extends JPanel { public AddressBookStatusBar() { setLayout(new FlowLayout(FlowLayout.LEFT)); this.statusBarString = new JLabel("Total: " + AddressBookForm.getTotalContacts()); add(this.statusBarString); } public void updateLabel() { contactsLabel.setText(AddressBookForm.getTotalContacts().toString()); } private JLabel statusBarString; private JLabel contactsLabel; } class AddressBookForm extends JPanel { public AddressBookForm() { // create form panel this.setLayout(new GridLayout(2, 1)); JPanel formPanel = new JPanel(); formPanel.setLayout(new GridLayout(4, 2)); firstName = new JTextField(20); lastName = new JTextField(20); telephone = new JTextField(20); email = new JTextField(20); JLabel firstNameLabel = new JLabel("First Name: ", JLabel.LEFT); formPanel.add(firstNameLabel); formPanel.add(firstName); JLabel lastNameLabel = new JLabel("Last Name: ", JLabel.LEFT); formPanel.add(lastNameLabel); formPanel.add(lastName); JLabel telephoneLabel = new JLabel("Telephone: ", JLabel.LEFT); formPanel.add(telephoneLabel); formPanel.add(telephone); JLabel emailLabel = new JLabel("Email: ", JLabel.LEFT); formPanel.add(emailLabel); formPanel.add(email); add(formPanel); // create button panel JPanel buttonPanel = new JPanel(); JButton insertButton = new JButton("Insert"); JButton displayButton = new JButton("Display"); ActionListener insertAction = new AddressBookListener(); ActionListener displayAction = new AddressBookListener(); insertButton.addActionListener(insertAction); displayButton.addActionListener(displayAction); buttonPanel.add(insertButton); buttonPanel.add(displayButton); add(buttonPanel); } public static int getTotalContacts() { return addressList.size(); } //void addContact(Person contact); private JTextField firstName; private JTextField lastName; private JTextField telephone; private JTextField email; private JLabel contacts; private static List<Person> addressList = new ArrayList<Person>(); private class AddressBookListener implements ActionListener { public void actionPerformed(ActionEvent e) { String buttonPressed = e.getActionCommand(); System.out.println(buttonPressed); if (buttonPressed == "Insert") { Person aPerson = new Person(firstName.getText(), lastName.getText(), telephone.getText(), email.getText()); addressList.add(aPerson); } else { for (Person p : addressList) { System.out.println(p); } } } } } My other question is why do I get the error, "int cannot be dereferenced contactsLabel.setText(AddressbookForm.getTotalContacts().toString()); Thanks!

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  • SQLiteException and SQLite error near "(": syntax error with Subsonic ActiveRecord

    - by nvuono
    I ran into an interesting error with the following LiNQ query using LiNQPad and when using Subsonic 3.0.x w/ActiveRecord within my project and wanted to share the error and resolution for anyone else who runs into it. The linq statement below is meant to group entries in the tblSystemsValues collection into their appropriate system and then extract the system with the highest ID. from ksf in KeySafetyFunction where ksf.Unit == 2 && ksf.Condition_ID == 1 join sys in tblSystems on ksf.ID equals sys.KeySafetyFunction join xval in (from t in tblSystemsValues group t by t.tblSystems_ID into groupedT select new { sysId = groupedT.Key, MaxID = groupedT.Max(g=>g.ID), MaxText = groupedT.First(gt2 => gt2.ID == groupedT.Max(g=>g.ID)).TextValue, MaxChecked = groupedT.First(gt2 => gt2.ID == groupedT.Max(g=>g.ID)).Checked }) on sys.ID equals xval.sysId select new {KSFDesc=ksf.Description, sys.Description, xval.MaxText, xval.MaxChecked} On its own, the subquery for grouping into groupedT works perfectly and the query to match up KeySafetyFunctions with their System in tblSystems also works perfectly on its own. However, when trying to run the completed query in linqpad or within my project I kept running into a SQLiteException SQLite Error Near "(" First I tried splitting the queries up within my project because I knew that I could just run a foreach loop over the results if necessary. However, I continued to receive the same exception! I eventually separated the query into three separate parts before I realized that it was the lazy execution of the queries that was killing me. It then became clear that adding the .ToList() specifier after the myProtectedSystem query below was the key to avoiding the lazy execution after combining and optimizing the query and being able to get my results despite the problems I encountered with the SQLite driver. // determine the max Text/Checked values for each system in tblSystemsValue var myProtectedValue = from t in tblSystemsValue.All() group t by t.tblSystems_ID into groupedT select new { sysId = groupedT.Key, MaxID = groupedT.Max(g => g.ID), MaxText = groupedT.First(gt2 => gt2.ID ==groupedT.Max(g => g.ID)).TextValue, MaxChecked = groupedT.First(gt2 => gt2.ID ==groupedT.Max(g => g.ID)).Checked}; // get the system description information and filter by Unit/Condition ID var myProtectedSystem = (from ksf in KeySafetyFunction.All() where ksf.Unit == 2 && ksf.Condition_ID == 1 join sys in tblSystem.All() on ksf.ID equals sys.KeySafetyFunction select new {KSFDesc = ksf.Description, sys.Description, sys.ID}).ToList(); // finally join everything together AFTER forcing execution with .ToList() var joined = from protectedSys in myProtectedSystem join protectedVal in myProtectedValue on protectedSys.ID equals protectedVal.sysId select new {protectedSys.KSFDesc, protectedSys.Description, protectedVal.MaxChecked, protectedVal.MaxText}; // print the gratifying debug results foreach(var protectedItem in joined) { System.Diagnostics.Debug.WriteLine(protectedItem.Description + ", " + protectedItem.KSFDesc + ", " + protectedItem.MaxText + ", " + protectedItem.MaxChecked); }

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  • Implementing union of Set using basic java array

    - by lupindeterd
    Note: This is an assignment. Hi, Continuing with my Set implementation using Java basic array, I'm now struggling with the 3 to last function namely the union. import java.io.*; class Set { private int numberOfElements = 0; private String[] setElements = new String[5]; private int maxNumberOfElements = 5; // constructor for our Set class public Set(int numberOfE, int setE, int maxNumberOfE) { int numberOfElements = numberOfE; String[] setElements = new String[setE]; int maxNumberOfElements = maxNumberOfE; } // Helper method to shorten/remove element of array since we're using basic array instead of ArrayList or HashSet from collection interface :( static String[] removeAt(int k, String[] arr) { final int L = arr.length; String[] ret = new String[L - 1]; System.arraycopy(arr, 0, ret, 0, k); System.arraycopy(arr, k + 1, ret, k, L - k - 1); return ret; } int findElement(String element) { int retval = 0; for ( int i = 0; i < setElements.length; i++) { if ( setElements[i] != null && setElements[i].equals(element) ) { return retval = i; } retval = -1; } return retval; } void add(String newValue) { int elem = findElement(newValue); if( numberOfElements < maxNumberOfElements && elem == -1 ) { setElements[numberOfElements] = newValue; numberOfElements++; } } int getLength() { if ( setElements != null ) { return setElements.length; } else { return 0; } } String[] emptySet() { setElements = new String[0]; return setElements; } Boolean isFull() { Boolean True = new Boolean(true); Boolean False = new Boolean(false); if ( setElements.length == maxNumberOfElements ){ return True; } else { return False; } } Boolean isEmpty() { Boolean True = new Boolean(true); Boolean False = new Boolean(false); if ( setElements.length == 0 ) { return True; } else { return False; } } void remove(String newValue) { for ( int i = 0; i < setElements.length; i++) { if ( setElements[i].equals(newValue) ) { setElements = removeAt(i,setElements); } } } int isAMember(String element) { int retval = -1; for ( int i = 0; i < setElements.length; i++ ) { if (setElements[i] != null && setElements[i].equals(element)) { return retval = i; } } return retval; } void printSet() { for ( int i = 0; i < setElements.length; i++) { System.out.println("Member elements on index: "+ i +" " + setElements[i]); } } String[] getMember() { String[] tempArray = new String[setElements.length]; for ( int i = 0; i < setElements.length; i++) { if(setElements[i] != null) { tempArray[i] = setElements[i]; } } return tempArray; } Set union(Set x, Set y) { String[] newtemparray = new String[x.getLength]; newtemparray = x.getMember; return x; } } // This is the SetDemo class that will make use of our Set class class SetDemo { public static void main(String[] args) { //get input from keyboard BufferedReader keyboard; InputStreamReader reader; String temp = ""; reader = new InputStreamReader(System.in); keyboard = new BufferedReader(reader); try { System.out.println("Enter string element to be added" ); temp = keyboard.readLine( ); System.out.println("You entered " + temp ); } catch (IOException IOerr) { System.out.println("There was an error during input"); } /* ************************************************************************** * Test cases for our new created Set class. * ************************************************************************** */ Set setA = new Set(1,10,10); setA.add(temp); setA.add("b"); setA.add("b"); setA.add("hello"); setA.add("world"); setA.add("six"); setA.add("seven"); setA.add("b"); int size = setA.getLength(); System.out.println("Set size is: " + size ); Boolean isempty = setA.isEmpty(); System.out.println("Set is empty? " + isempty ); int ismember = setA.isAMember("sixb"); System.out.println("Element six is member of setA? " + ismember ); Boolean output = setA.isFull(); System.out.println("Set is full? " + output ); setA.printSet(); int index = setA.findElement("world"); System.out.println("Element b located on index: " + index ); setA.remove("b"); setA.emptySet(); int resize = setA.getLength(); System.out.println("Set size is: " + resize ); setA.printSet(); Set setB = new Set(0,10,10); Set SetA = setA.union(setB,setA); } } Ok the method in question will be the implementation of union. As such this: Set union(Set x, Set y) { String[] newtemparray = new String[x.getLength]; newtemparray = x.getMember; return x; } I got this error: symbol : variable getLength location: class Set String[] newtemparray = new String[x.getLength]; ^ d:\javaprojects\Set.java:122: cannot find symbol symbol : variable getMember location: class Set newtemparray = x.getMember; ^ 2 errors My approach for union would be: *) create temporary array of string with size of the object x length. *) store object x members to temporary array by looping the object and calling the getMember *) loop object y members and check if element exist against temporary array. *) discard if it exist/add if it is not there *) return obj x with the union array. thanks, lupin

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  • Casting an object using 'as' returns null: myObject = newObject as MyObject; // null

    - by John Russell
    I am trying to create a custom object in AS3 to pass information to and from a server, which in this case will be Red5. In the below screenshots you will see that I am able to send a request for an object from as3, and receive it successfully from the java server. However, when I try to cast the received object to my defined objectType using 'as', it takes the value of null. It is my understanding that that when using "as" your checking to see if your variable is a member of the specified data type. If the variable is not, then null will be returned. This screenshot illustrates that I am have successfully received my object 'o' from red5 and I am just about to cast it to the (supposedly) identical datatype testObject of LobbyData: However, when testObject = o as LobbyData; runs, it returns null. :( Below you will see my specifications both on the java server and the as3 client. I am confident that both objects are identical in every way, but for some reason flash does not think so. I have been pulling my hair out for a long time, does anyone have any thoughts? AS3 Object: import flash.utils.IDataInput; import flash.utils.IDataOutput; import flash.utils.IExternalizable; import flash.net.registerClassAlias; [Bindable] [RemoteClass(alias = "myLobbyData.LobbyData")] public class LobbyData implements IExternalizable { private var sent:int; // java sentinel private var u:String; // red5 username private var sen:int; // another sentinel? private var ui:int; // fb uid private var fn:String; // fb name private var pic:String; // fb pic private var inb:Boolean; // is in the table? private var t:int; // table number private var s:int; // seat number public function setSent(sent:int):void { this.sent = sent; } public function getSent():int { return sent; } public function setU(u:String):void { this.u = u; } public function getU():String { return u; } public function setSen(sen:int):void { this.sen = sen; } public function getSen():int { return sen; } public function setUi(ui:int):void { this.ui = ui; } public function getUi():int { return ui; } public function setFn(fn:String):void { this.fn = fn; } public function getFn():String { return fn; } public function setPic(pic:String):void { this.pic = pic; } public function getPic():String { return pic; } public function setInb(inb:Boolean):void { this.inb = inb; } public function getInb():Boolean { return inb; } public function setT(t:int):void { this.t = t; } public function getT():int { return t; } public function setS(s:int):void { this.s = s; } public function getS():int { return s; } public function readExternal(input:IDataInput):void { sent = input.readInt(); u = input.readUTF(); sen = input.readInt(); ui = input.readInt(); fn = input.readUTF(); pic = input.readUTF(); inb = input.readBoolean(); t = input.readInt(); s = input.readInt(); } public function writeExternal(output:IDataOutput):void { output.writeInt(sent); output.writeUTF(u); output.writeInt(sen); output.writeInt(ui); output.writeUTF(fn); output.writeUTF(pic); output.writeBoolean(inb); output.writeInt(t); output.writeInt(s); } } Java Object: package myLobbyData; import org.red5.io.amf3.IDataInput; import org.red5.io.amf3.IDataOutput; import org.red5.io.amf3.IExternalizable; public class LobbyData implements IExternalizable { private static final long serialVersionUID = 115280920; private int sent; // java sentinel private String u; // red5 username private int sen; // another sentinel? private int ui; // fb uid private String fn; // fb name private String pic; // fb pic private Boolean inb; // is in the table? private int t; // table number private int s; // seat number public void setSent(int sent) { this.sent = sent; } public int getSent() { return sent; } public void setU(String u) { this.u = u; } public String getU() { return u; } public void setSen(int sen) { this.sen = sen; } public int getSen() { return sen; } public void setUi(int ui) { this.ui = ui; } public int getUi() { return ui; } public void setFn(String fn) { this.fn = fn; } public String getFn() { return fn; } public void setPic(String pic) { this.pic = pic; } public String getPic() { return pic; } public void setInb(Boolean inb) { this.inb = inb; } public Boolean getInb() { return inb; } public void setT(int t) { this.t = t; } public int getT() { return t; } public void setS(int s) { this.s = s; } public int getS() { return s; } @Override public void readExternal(IDataInput input) { sent = input.readInt(); u = input.readUTF(); sen = input.readInt(); ui = input.readInt(); fn = input.readUTF(); pic = input.readUTF(); inb = input.readBoolean(); t = input.readInt(); s = input.readInt(); } @Override public void writeExternal(IDataOutput output) { output.writeInt(sent); output.writeUTF(u); output.writeInt(sen); output.writeInt(ui); output.writeUTF(fn); output.writeUTF(pic); output.writeBoolean(inb); output.writeInt(t); output.writeInt(s); } } AS3 Client: public function refreshRoom(event:Event) { var resp:Responder=new Responder(handleResp,null); ncLobby.call("getLobbyData", resp, null); } public function handleResp(o:Object):void { var testObject:LobbyData=new LobbyData; testObject = o as LobbyData; trace(testObject); } Java Client public LobbyData getLobbyData(String param) { LobbyData lobbyData1 = new LobbyData(); lobbyData1.setSent(5); lobbyData1.setU("lawlcats"); lobbyData1.setSen(5); lobbyData1.setUi(5); lobbyData1.setFn("lulz"); lobbyData1.setPic("lulzagain"); lobbyData1.setInb(true); lobbyData1.setT(5); lobbyData1.setS(5); return lobbyData1; }

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  • For loop from assembly to C

    - by FranXh
    I have a bomb project where I need to defuse certain phases by finding "pas phrases" that will defuse the bomb. Right now I have been working with phase_2, for which the assembly code is shown below. Phase_2 requires as an input 6 numbers, which I need to find in order to defuse this phase. I analyzed this assembly, and I came up with the C code below, that covers lines from 40101c to 401044. It is basically a for loop that makes sure that elements t[0]==t[3], t[1]==t[4] and t[2]==t[5] that the user inputs, are equal. According to my logic, the user can input any 6 numbers as long as the above condition is satisfied. Say 1, 2, 3, 1, 2, 3 would be a valid "pas phrase". However this solution does not convince me for some reason. Am I doing something wrong? 0000000000400ffc <phase_2>: 400ffc: 48 89 5c 24 e0 mov %rbx,-0x20(%rsp) 401001: 48 89 6c 24 e8 mov %rbp,-0x18(%rsp) 401006: 4c 89 64 24 f0 mov %r12,-0x10(%rsp) 40100b: 4c 89 6c 24 f8 mov %r13,-0x8(%rsp) 401010: 48 83 ec 48 sub $0x48,%rsp 401014: 48 89 e6 mov %rsp,%rsi 401017: e8 65 0a 00 00 callq 401a81 <read_six_numbers> 40101c: 48 89 e5 mov %rsp,%rbp 40101f: 4c 8d 6c 24 0c lea 0xc(%rsp),%r13 401024: 41 bc 00 00 00 00 mov $0x0,%r12d 40102a: 48 89 eb mov %rbp,%rbx 40102d: 8b 45 0c mov 0xc(%rbp),%eax 401030: 39 45 00 cmp %eax,0x0(%rbp) 401033: 74 05 je 40103a <phase_2+0x3e> 401035: e8 2d 09 00 00 callq 401967 <_GLOBAL_RESET_> 40103a: 44 03 23 add (%rbx),%r12d 40103d: 48 83 c5 04 add $0x4,%rbp 401041: 4c 39 ed cmp %r13,%rbp 401044: 75 e4 jne 40102a <phase_2+0x2e> 401046: 45 85 e4 test %r12d,%r12d 401049: 75 05 jne 401050 <phase_2+0x54> 40104b: e8 17 09 00 00 callq 401967 <_GLOBAL_RESET_> 401050: 48 8b 5c 24 28 mov 0x28(%rsp),%rbx 401055: 48 8b 6c 24 30 mov 0x30(%rsp),%rbp 40105a: 4c 8b 64 24 38 mov 0x38(%rsp),%r12 40105f: 4c 8b 6c 24 40 mov 0x40(%rsp),%r13 401064: 48 83 c4 48 add $0x48,%rsp 401068: c3 for (int i=0; i<3; i++){ if(t[i] != t[i+3]){ explode(); } }

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  • Amusing or Sad? Network Solutions

    - by dbasnett
    When I got sick my email ended up in every drug sellers email list. Some days I get over 200 emails selling everything from Viagra to Xanax. Either they don't know what my condition is or they are telling me you are a goner, might as well chill-ax and have a good time. In order to cut down on the mail being downloaded I thought I would add all of the Junk email senders from Outlook to my Network Solution mail server. Much to my amazement I could not find that import Spammers button, so I submitted a tech support request. Here is the response: Thank you for contacting Network Solutions Customer Service Department. We are committed to creating the best Customer experience possible. One of the first ways we can demonstrate our commitment to this goal is to quickly and efficiently handle your recent request. We apologize for any inconvenience this might have caused you. With regard to your concern, please be advised that we cannot import blocked senders in to you e-mail servers. An alternative option is for you to create a Custom Filter that filters unwanted e-mails. To create a Custom Filter: Open a Web browser (e.g., Netscape, Microsoft Internet Explorer, etc.). Type mail.[domain name].[ext] in the address line. Login to your Network Solutions email account. Click on the Configuration left menu tab. Click on the Custom Filter link. Type the rule name. blah, blah, blah Basically add them one at a time. "We are committed to creating the best Customer experience possible." No you are not. You are trying to squeeze every nickle you can out of me. "With regard to your concern, please be advised that we cannot import blocked senders in to you e-mail servers." Maybe I should apply for a job to write those ten complicated lines of code... Maybe I should question my choice of vendors, because if they truly "cannot" then they are to stupid to have my business. It is both amusing and sad. I'll be posting this in every forum I am a member of.

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  • how to read values from the remote OPC Server

    - by Shailesh Jaiswal
    I have created one asp.net web service. In this web service I am using the web method as follows. The web service is related to the OPC ( OLE for process control) public string ReadServerItems(string ServerName) { string txt = ""; ArrayList obj = new ArrayList(); XmlServer Srv = new XmlServer("XDAGW.CS.WCF.Eval.1"); RequestOptions opt = new RequestOptions(); ReadRequestItemList iList = new ReadRequestItemList(); iList.Items = new ReadRequestItem[3]; iList.Items[0] = new ReadRequestItem(); iList.Items[0].ItemName = "ServerInfo.ConnectedClients"; iList.Items[1] = new ReadRequestItem(); iList.Items[1].ItemName = "ServerInfo.TotalGroups"; iList.Items[2] = new ReadRequestItem(); iList.Items[2].ItemName = "EventSources.Area1.Tracking"; ReplyItemList rslt; OPCError[] err; ReplyBase reply = Srv.Read(opt, iList, out rslt, out err); if ((rslt == null)) txt += err[0].Text; else { foreach (xmldanet.xmlda.ItemValue iv in rslt.Items) { txt += iv.ItemName; if (iv.ResultID == null) // success { txt += " = " + iv.Value.ToString() + "\r\n"; obj.Add(txt); } else txt += " : Error: " + iv.ResultID.Name + "\r\n"; } } return txt; } I am using the namespaces as follows using xmldanet; using xmldanet.xmlda; I have installed XMLDA.NET client component evaluation. In this there is an in built Test client which successfully reads the values of these data items from the remote OPC server. I also provides the template through which we can build the OPC based applications. In the above code I am trying to read the values of the data items but i am not able to read the values. I have applied the breakpoint. In that I can see that the condition if (iv.ResultID == null) becomes false & also there is null values in the variable rslt. Please tell me where I am doing mistake ? how should I correct my mistake ? can provide me the correct code ?

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  • A lock could not obtained within the time requested issue

    - by Wayne Daly
    The title is the error I'm getting, when I click load my program freezes. I assume its because I'm doing a statement inside a statement, but from what I see its the only solution to my issue. By loading I want to just repopulate the list of patients, but to do so I need to do their conditions also. The code works, the bottom method is what I'm trying to fix. I think the issue is that I have 2 statements open but I am not sure. load: public void DatabaseLoad() { try { String Name = "Wayne"; String Pass= "Wayne"; String Host = "jdbc:derby://localhost:1527/Patients"; Connection con = DriverManager.getConnection( Host,Name, Pass); PatientList.clear(); Statement stmt8 = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); String SQL8 = "SELECT * FROM PATIENTS"; ResultSet rs8 = stmt8.executeQuery( SQL8 ); ArrayList<PatientCondition> PatientConditions1 = new ArrayList(); while(rs8.next()) { PatientConditions1 = LoadPatientConditions(); } Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); String SQL = "SELECT * FROM PATIENTS"; ResultSet rs = stmt.executeQuery( SQL ); while(rs.next()) { int id = (rs.getInt("ID")); String name = (rs.getString("NAME")); int age = (rs.getInt("AGE")); String address = (rs.getString("ADDRESS")); String sex = (rs.getString("SEX")); String phone = (rs.getString("PHONE")); Patient p = new Patient(id, name, age, address, sex, phone, PatientConditions1); PatientList.add(p); } UpdateTable(); UpdateAllViews(); DefaultListModel PatientListModel = new DefaultListModel(); for (Patient s : PatientList) { PatientListModel.addElement(s.getAccountNumber() + "-" + s.getName()); } PatientJList.setModel(PatientListModel); } catch(SQLException err) { System.out.println(err.getMessage()); } } This is the method that returns the arraylist of patient conditions public ArrayList LoadPatientConditions() { ArrayList<PatientCondition> PatientConditionsTemp = new ArrayList(); try { String Name = "Wayne"; String Pass= "Wayne"; String Host = "jdbc:derby://localhost:1527/Patients"; Connection con = DriverManager.getConnection( Host,Name, Pass); Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); String SQL = "SELECT * FROM PATIENTCONDITIONS"; ResultSet rs5 = stmt.executeQuery( SQL ); int e = 0; while(rs5.next()) { e++; String ConName = (rs5.getString("CONDITION")); PatientCondition k = new PatientCondition(e,ConName); PatientConditionsTemp.add(k); } } catch(SQLException err) { System.out.println(err.getMessage()); } return PatientConditionsTemp; }

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  • stop and split generated sequence at repeats - clojure

    - by fitzsnaggle
    I am trying to make a sequence that will only generate values until it finds the following conditions and return the listed results: case head = 0 - return {:origin [all generated except 0] :pattern 0} 1 - return {:origin nil :pattern [all-generated-values] } repeated-value - {:origin [values-before-repeat] :pattern [values-after-repeat] { ; n = int ; x = int ; hist - all generated values ; Keeps the head below x (defn trim-head [head x] (loop [head head] (if (> head x) (recur (- head x)) head))) ; Generates the next head (defn next-head [head x n] (trim-head (* head n) x)) (defn row [x n] (iterate #(next-head % x n) n)) ; Generates a whole row - ; Rows are a max of x - 1. (take (- x 1) (row 11 3)) Examples of cases to stop before reaching end of row: [9 8 4 5 6 7 4] - '4' is repeated so STOP. Return preceding as origin and rest as pattern. {:origin [9 8] :pattern [4 5 6 7]} [4 5 6 1] - found a '1' so STOP, so return everything as pattern {:origin nil :pattern [4 5 6 1]} [3 0] - found a '0' so STOP {:origin [3] :pattern [0]} :else if the sequences reaches a length of x - 1: {:origin [all values generated] :pattern nil} The Problem I have used partition-by with some success to split the groups at the point where a repeated value is found, but would like to do this lazily. Is there some way I can use take-while, or condp, or the :while clause of the for loop to make a condition that partitions when it finds repeats? Some Attempts (take 2 (partition-by #(= 1 %) (row 11 4))) (for [p (partition-by #(stop-match? %) head) (iterate #(next-head % x n) n) :while (or (not= (last p) (or 1 0 n) (nil? (rest p))] {:origin (first p) :pattern (concat (second p) (last p))})) # Updates What I really want to be able to do is find out if a value has repeated and partition the seq without using the index. Is that possible? Something like this - { (defn row [x n] (loop [hist [n] head (gen-next-head (first hist) x n) steps 1] (if (>= (- x 1) steps) (case head 0 {:origin [hist] :pattern [0]} 1 {:origin nil :pattern (conj hist head)} ; Speculative from here on out (let [p (partition-by #(apply distinct? %) (conj hist head))] (if-not (nil? (next p)) ; One partition if no repeats. {:origin (first p) :pattern (concat (second p) (nth 3 p))} (recur (conj hist head) (gen-next-head head x n) (inc steps))))) {:origin hist :pattern nil}))) }

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  • How to make freelance clients understand the costs of developing and maintaining mature products?

    - by John
    I have a freelance web application project where the client requests new features every two weeks or so. I am unable to anticipate the requirements of upcoming features. So when the client requests a new feature, one of several things may happen: I implement the feature with ease because it is compatible with the existing platform I implement the feature with difficulty because I have to rewrite a significant portion of the platform's foundation Client withdraws request because it costs too much to implement against existing platform At the beginning of the project, for about six months, all feature requests fell under category 1) because the system was small and agile. But for the past six months, most feature implementation fell under category 2). The system is mature, forcing me to refactor and test everytime I want to add new modules. Additionally, I find myself breaking things that use to work, and fixing it (I don't get paid for this). The client is starting to express frustration at the time and cost for me to implement new features. To them, many of the feature requests are of the same scale as the features they requested six months ago. For example, a client would ask, "If it took you 1 week to build a ticketing system last year, why does it take you 1 month to build an event registration system today? An event registration system is much simpler than a ticketing system. It should only take you 1 week!" Because of this scenario, I fear feature requests will soon land in category 3). In fact, I'm already eating a lot of the cost myself because I volunteer many hours to support the project. The client is often shocked when I tell him honestly the time it takes to do something. The client always compares my estimates against the early months of a project. I don't think they're prepared for what it really costs to develop, maintain and support a mature web application. When working on a salary for a full time company, managers were more receptive of my estimates and even encouraged me to pad my numbers to prepare for the unexpected. Is there a way to condition my clients to think the same way? Can anyone offer advice on how I can continue to work on this web project without eating too much of the cost myself? Additional info - I've only been freelancing full time for 1 year. I don't yet have the high end clients, but I'm slowly getting there. I'm getting better quality clients as time goes by.

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  • Custom language - FOR loop in a clojure interpeter?

    - by Mark
    I have a basic interpreter in clojure. Now i need to implement for (initialisation; finish-test; loop-update) { statements } Implement a similar for-loop for the interpreted language. The pattern will be: (for variable-declarations end-test loop-update do statement) The variable-declarations will set up initial values for variables.The end-test returns a boolean, and the loop will end if end-test returns false. The statement is interpreted followed by the loop-update for each pass of the loop. Examples of use are: (run ’(for ((i 0)) (< i 10) (set i (+ 1 i)) do (println i))) (run ’(for ((i 0) (j 0)) (< i 10) (seq (set i (+ 1 i)) (set j (+ j (* 2 i)))) do (println j))) inside my interpreter. I will attach my interpreter code I got so far. Any help is appreciated. Interpreter (declare interpret make-env) ;; needed as language terms call out to 'interpret' (def do-trace false) ;; change to 'true' to show calls to 'interpret' ;; simple utilities (def third ; return third item in a list (fn [a-list] (second (rest a-list)))) (def fourth ; return fourth item in a list (fn [a-list] (third (rest a-list)))) (def run ; make it easy to test the interpreter (fn [e] (println "Processing: " e) (println "=> " (interpret e (make-env))))) ;; for the environment (def make-env (fn [] '())) (def add-var (fn [env var val] (cons (list var val) env))) (def lookup-var (fn [env var] (cond (empty? env) 'error (= (first (first env)) var) (second (first env)) :else (lookup-var (rest env) var)))) ;; for terms in language ;; -- define numbers (def is-number? (fn [expn] (number? expn))) (def interpret-number (fn [expn env] expn)) ;; -- define symbols (def is-symbol? (fn [expn] (symbol? expn))) (def interpret-symbol (fn [expn env] (lookup-var env expn))) ;; -- define boolean (def is-boolean? (fn [expn] (or (= expn 'true) (= expn 'false)))) (def interpret-boolean (fn [expn env] expn)) ;; -- define functions (def is-function? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'lambda (first expn))))) (def interpret-function ; keep function definitions as they are written (fn [expn env] expn)) ;; -- define addition (def is-plus? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '+ (first expn))))) (def interpret-plus (fn [expn env] (+ (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define subtraction (def is-minus? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '- (first expn))))) (def interpret-minus (fn [expn env] (- (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define multiplication (def is-times? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '* (first expn))))) (def interpret-times (fn [expn env] (* (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define division (def is-divides? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '/ (first expn))))) (def interpret-divides (fn [expn env] (/ (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define equals test (def is-equals? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '= (first expn))))) (def interpret-equals (fn [expn env] (= (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define greater-than test (def is-greater-than? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '> (first expn))))) (def interpret-greater-than (fn [expn env] (> (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define not (def is-not? (fn [expn] (and (list? expn) (= 2 (count expn)) (= 'not (first expn))))) (def interpret-not (fn [expn env] (not (interpret (second expn) env)))) ;; -- define or (def is-or? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'or (first expn))))) (def interpret-or (fn [expn env] (or (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define and (def is-and? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'and (first expn))))) (def interpret-and (fn [expn env] (and (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define print (def is-print? (fn [expn] (and (list? expn) (= 2 (count expn)) (= 'println (first expn))))) (def interpret-print (fn [expn env] (println (interpret (second expn) env)))) ;; -- define with (def is-with? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'with (first expn))))) (def interpret-with (fn [expn env] (interpret (third expn) (add-var env (first (second expn)) (interpret (second (second expn)) env))))) ;; -- define if (def is-if? (fn [expn] (and (list? expn) (= 4 (count expn)) (= 'if (first expn))))) (def interpret-if (fn [expn env] (cond (interpret (second expn) env) (interpret (third expn) env) :else (interpret (fourth expn) env)))) ;; -- define function-application (def is-function-application? (fn [expn env] (and (list? expn) (= 2 (count expn)) (is-function? (interpret (first expn) env))))) (def interpret-function-application (fn [expn env] (let [function (interpret (first expn) env)] (interpret (third function) (add-var env (first (second function)) (interpret (second expn) env)))))) ;; the interpreter itself (def interpret (fn [expn env] (cond do-trace (println "Interpret is processing: " expn)) (cond ; basic values (is-number? expn) (interpret-number expn env) (is-symbol? expn) (interpret-symbol expn env) (is-boolean? expn) (interpret-boolean expn env) (is-function? expn) (interpret-function expn env) ; built-in functions (is-plus? expn) (interpret-plus expn env) (is-minus? expn) (interpret-minus expn env) (is-times? expn) (interpret-times expn env) (is-divides? expn) (interpret-divides expn env) (is-equals? expn) (interpret-equals expn env) (is-greater-than? expn) (interpret-greater-than expn env) (is-not? expn) (interpret-not expn env) (is-or? expn) (interpret-or expn env) (is-and? expn) (interpret-and expn env) (is-print? expn) (interpret-print expn env) ; special syntax (is-with? expn) (interpret-with expn env) (is-if? expn) (interpret-if expn env) ; functions (is-function-application? expn env) (interpret-function-application expn env) :else 'error))) ;; tests of using environment (println "Environment tests:") (println (add-var (make-env) 'x 1)) (println (add-var (add-var (add-var (make-env) 'x 1) 'y 2) 'x 3)) (println (lookup-var '() 'x)) (println (lookup-var '((x 1)) 'x)) (println (lookup-var '((x 1) (y 2)) 'x)) (println (lookup-var '((x 1) (y 2)) 'y)) (println (lookup-var '((x 3) (y 2) (x 1)) 'x)) ;; examples of using interpreter (println "Interpreter examples:") (run '1) (run '2) (run '(+ 1 2)) (run '(/ (* (+ 4 5) (- 2 4)) 2)) (run '(with (x 1) x)) (run '(with (x 1) (with (y 2) (+ x y)))) (run '(with (x (+ 2 4)) x)) (run 'false) (run '(not false)) (run '(with (x true) (with (y false) (or x y)))) (run '(or (= 3 4) (> 4 3))) (run '(with (x 1) (if (= x 1) 2 3))) (run '(with (x 2) (if (= x 1) 2 3))) (run '((lambda (n) (* 2 n)) 4)) (run '(with (double (lambda (n) (* 2 n))) (double 4))) (run '(with (sum-to (lambda (n) (if (= n 0) 0 (+ n (sum-to (- n 1)))))) (sum-to 100))) (run '(with (x 1) (with (f (lambda (n) (+ n x))) (with (x 2) (println (f 3))))))

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  • c++ class member functions selected by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched stackoverflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instatiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state info was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • Reading a child process's /proc/pid/mem file from the parent

    - by Amittai Aviram
    In the program below, I am trying to cause the following to happen: Process A assigns a value to a stack variable a. Process A (parent) creates process B (child) with PID child_pid. Process B calls function func1, passing a pointer to a. Process B changes the value of variable a through the pointer. Process B opens its /proc/self/mem file, seeks to the page containing a, and prints the new value of a. Process A (at the same time) opens /proc/child_pid/mem, seeks to the right page, and prints the new value of a. The problem is that, in step 6, the parent only sees the old value of a in /proc/child_pid/mem, while the child can indeed see the new value in its /proc/self/mem. Why is this the case? Is there any way that I can get the parent to to see the child's changes to its address space through the /proc filesystem? #include <fcntl.h> #include <stdbool.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <unistd.h> #define PAGE_SIZE 0x1000 #define LOG_PAGE_SIZE 0xc #define PAGE_ROUND_DOWN(v) ((v) & (~(PAGE_SIZE - 1))) #define PAGE_ROUND_UP(v) (((v) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1))) #define OFFSET_IN_PAGE(v) ((v) & (PAGE_SIZE - 1)) # if defined ARCH && ARCH == 32 #define BP "ebp" #define SP "esp" #else #define BP "rbp" #define SP "rsp" #endif typedef struct arg_t { int a; } arg_t; void func1(void * data) { arg_t * arg_ptr = (arg_t *)data; printf("func1: old value: %d\n", arg_ptr->a); arg_ptr->a = 53; printf("func1: address: %p\n", &arg_ptr->a); printf("func1: new value: %d\n", arg_ptr->a); } void expore_proc_mem(void (*fn)(void *), void * data) { off_t frame_pointer, stack_start; char buffer[PAGE_SIZE]; const char * path = "/proc/self/mem"; int child_pid, status; int parent_to_child[2]; int child_to_parent[2]; arg_t * arg_ptr; off_t child_offset; asm volatile ("mov %%"BP", %0" : "=m" (frame_pointer)); stack_start = PAGE_ROUND_DOWN(frame_pointer); printf("Stack_start: %lx\n", (unsigned long)stack_start); arg_ptr = (arg_t *)data; child_offset = OFFSET_IN_PAGE((off_t)&arg_ptr->a); printf("Address of arg_ptr->a: %p\n", &arg_ptr->a); pipe(parent_to_child); pipe(child_to_parent); bool msg; int child_mem_fd; char child_path[0x20]; child_pid = fork(); if (child_pid == -1) { perror("fork"); exit(EXIT_FAILURE); } if (!child_pid) { close(child_to_parent[0]); close(parent_to_child[1]); printf("CHILD (pid %d, parent pid %d).\n", getpid(), getppid()); fn(data); msg = true; write(child_to_parent[1], &msg, 1); child_mem_fd = open("/proc/self/mem", O_RDONLY); if (child_mem_fd == -1) { perror("open (child)"); exit(EXIT_FAILURE); } printf("CHILD: child_mem_fd: %d\n", child_mem_fd); if (lseek(child_mem_fd, stack_start, SEEK_SET) == (off_t)-1) { perror("lseek"); exit(EXIT_FAILURE); } if (read(child_mem_fd, buffer, sizeof(buffer)) != sizeof(buffer)) { perror("read"); exit(EXIT_FAILURE); } printf("CHILD: new value %d\n", *(int *)(buffer + child_offset)); read(parent_to_child[0], &msg, 1); exit(EXIT_SUCCESS); } else { printf("PARENT (pid %d, child pid %d)\n", getpid(), child_pid); printf("PARENT: child_offset: %lx\n", child_offset); read(child_to_parent[0], &msg, 1); printf("PARENT: message from child: %d\n", msg); snprintf(child_path, 0x20, "/proc/%d/mem", child_pid); printf("PARENT: child_path: %s\n", child_path); child_mem_fd = open(path, O_RDONLY); if (child_mem_fd == -1) { perror("open (child)"); exit(EXIT_FAILURE); } printf("PARENT: child_mem_fd: %d\n", child_mem_fd); if (lseek(child_mem_fd, stack_start, SEEK_SET) == (off_t)-1) { perror("lseek"); exit(EXIT_FAILURE); } if (read(child_mem_fd, buffer, sizeof(buffer)) != sizeof(buffer)) { perror("read"); exit(EXIT_FAILURE); } printf("PARENT: new value %d\n", *(int *)(buffer + child_offset)); close(child_mem_fd); printf("ENDING CHILD PROCESS.\n"); write(parent_to_child[1], &msg, 1); if (waitpid(child_pid, &status, 0) == -1) { perror("waitpid"); exit(EXIT_FAILURE); } } } int main(void) { arg_t arg; arg.a = 42; printf("In main: address of arg.a: %p\n", &arg.a); explore_proc_mem(&func1, &arg.a); return EXIT_SUCCESS; } This program produces the output below. Notice that the value of a (boldfaced) differs between parent's and child's reading of the /proc/child_pid/mem file. In main: address of arg.a: 0x7ffffe1964f0 Stack_start: 7ffffe196000 Address of arg_ptr-a: 0x7ffffe1964f0 PARENT (pid 20376, child pid 20377) PARENT: child_offset: 4f0 CHILD (pid 20377, parent pid 20376). func1: old value: 42 func1: address: 0x7ffffe1964f0 func1: new value: 53 PARENT: message from child: 1 CHILD: child_mem_fd: 4 PARENT: child_path: /proc/20377/mem CHILD: new value 53 PARENT: child_mem_fd: 7 PARENT: new value 42 ENDING CHILD PROCESS.

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  • How to return the date value from DatePickerDialog in Android?

    - by user1855222
    I am new to android . I ve created a Date picker in android using following guide .http://developer.android.com/guide/topics/ui/controls/pickers.html public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener { StringBuilder sb = new StringBuilder(); public static String date; @Override public Dialog onCreateDialog(Bundle savedInstanceState) { // Use the current date as the default date in the picker final Calendar c = Calendar.getInstance(); int year = c.get(Calendar.YEAR); int month = c.get(Calendar.MONTH); int day = c.get(Calendar.DAY_OF_MONTH); // Create a new instance of DatePickerDialog and return it return new DatePickerDialog(getActivity(), this, year, month, day); } public void onDateSet(DatePicker view, int year, int month, int day) { // Do something with the date chosen by the user sb.append(year); sb.append('-'); sb.append(month+1); sb.append('-'); sb.append(day); date = sb.toString(); System.out.println("The date is "+date); } I need to return this date value (date = sb.toString()) to my MainActivity . Since the onDateSet method is void what should I do ? Additional Information - DatePickerDialog Triggers at the MainActivity class ,But not with single button click . There are several processes happens in side a single button , Date picker will triggers only when certain condition is met . I do not want to display the date value either . Just want it returned for further processing. Appreciate any kind of guidance Changed onDataset method and justshow() public void onDateSet(DatePicker view, int year, int month, int day) { // Do something with the date chosen by the user sb.append(year); sb.append('-'); sb.append(month+1); sb.append('-'); sb.append(day); date = sb.toString(); MainActivity.newdate=sb.toString(); System.out.println("The date is "+MainActivity.newdate); } public void justShow(){ System.out.println("The date is "+MainActivity.newdate); } This is the relevant Part From Main(After making changes suggested in first reply ) DateToken mydate=new DateToken(); String test=dayvals.get(0); DialogFragment df=new DatePickerFragment(); if(test.equalsIgnoreCase("day")){ df.show(getSupportFragmentManager(), "DatePik"); } System.out.println("Date is on Main"+newdate); DatePickerFragment dpf=new DatePickerFragment(); dpf.justShow(); newdate is the static String , but still outputs null. In both MainActivity and justShow methods . But in onDataSet method date outputs correctly

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  • C Programming: malloc() for a 2D array (using pointer-to-pointer)

    - by vikramtheone
    Hi Guys, yesterday I had posted a question: How should I pass a pointer to a function and allocate memory for the passed pointer from inside the called function? From the answers I got, I was able to understand what mistake I was doing. I'm facing a new problem now, can anyone help out with this? I want to dynamically allocate a 2D array, so I'm passing a Pointer-to-Pointer from my main() to another function called alloc_2D_pixels(...), where I use malloc(...) and for(...) loop to allocate memory for the 2D array. Well, after returning from the alloc_2D_pixels(...) function, the pointer-to-pointer still remains NULL, so naturally, when I try accessing or try to free(...) the Pointer-to-Pointer, the program hangs. Can anyone suggest me what mistakes I'm doing here? Help!!! Vikram SOURCE: main() { unsigned char **ptr; unsigned int rows, cols; if(alloc_2D_pixels(&ptr, rows, cols)==ERROR) // Satisfies this condition printf("Memory for the 2D array not allocated"); // NO ERROR is returned if(ptr == NULL) // ptr is NULL so no memory was allocated printf("Yes its NULL!"); // Because ptr is NULL, with any of these 3 statements below the program HANGS ptr[0][0] = 10; printf("Element: %d",ptr[0][0]); free_2D_alloc(&ptr); } signed char alloc_2D_pixels(unsigned char ***memory, unsigned int rows, unsigned int cols) { signed char status = NO_ERROR; memory = malloc(rows * sizeof(unsigned char** )); if(memory == NULL) { status = ERROR; printf("ERROR: Memory allocation failed!"); } else { int i; for(i = 0; i< cols; i++) { memory[i] = malloc(cols * sizeof(unsigned char)); if(memory[i]==NULL) { status = ERROR; printf("ERROR: Memory allocation failed!"); } } } // Inserted the statements below for debug purpose only memory[0][0] = (unsigned char)10; // I'm able to access the array from printf("\nElement %d",memory[0][0]); // here with no problems return status; } void free_2D_pixels(unsigned char ***ptr, unsigned int rows) { int i; for(i = 0; i < rows; i++) { free(ptr[i]); } free(ptr); }

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  • How to solve Memory leaks in Lib Xml Parser in objective-C where the list is returned?

    - by Madan Mohan
    Hi Guys, I got leaks in Lib Xml Parser while retrieving the data from the net, Here in the below code, I have allocated the list - (void)getCustomersList { // make an operation so we can push it into the queue SEL method = @selector(parseForData); NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:method object:nil]; customersTempList = [[NSMutableArray alloc] initWithCapacity:20];// allocated list [self.retrieverQueue addOperation:op]; [op release]; } // return each recode // in parser .m class one of the condition in endElement where it shows a leak. else if(0 == strncmp((const char *)localname, kCustomerElement, kCustomerElementLength)) { [customersTempList addObject:customer]; printf("\n no of objects in temp list:%d", [customersTempList count]); if ([customersTempList count] == 20) { NSMutableArray* argsList = [customersTempList copy];//////////////////////here it is showing leak. printf("\n Calling reload data with %d new objects", [argsList count]); SEL selector = @selector(parser:addCustomerObject:); NSMethodSignature *sig = [(id)self.delegate methodSignatureForSelector:selector]; if(nil != sig && [self.delegate respondsToSelector:selector]) { NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig]; [invocation retainArguments]; [invocation setTarget:self.delegate]; [invocation setSelector:selector]; [invocation setArgument:&self atIndex:2]; [invocation setArgument:&argsList atIndex:3]; [invocation performSelectorOnMainThread:@selector(invoke) withObject:NULL waitUntilDone:NO]; } [customersTempList removeAllObjects]; } } // returned the list after all the records are stored in the list else if(0 == strncmp((const char *)localname, kCustomersElement, kCustomersElementLength)) { printf("\n Calling reload data with %d new objects", [customersTempList count]); NSMutableArray* argsList = [customersTempList copy]; printf("\n Calling reload data with %d new objects", [argsList count]); SEL selector = @selector(parser:addCustomerObject:); NSMethodSignature *sig = [(id)self.delegate methodSignatureForSelector:selector]; if(nil != sig && [self.delegate respondsToSelector:selector]) { NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig]; [invocation retainArguments]; [invocation setTarget:self.delegate]; [invocation setSelector:selector]; [invocation setArgument:&self atIndex:2]; [invocation setArgument:&argsList atIndex:3]; [invocation performSelectorOnMainThread:@selector(invoke) withObject:NULL waitUntilDone:NO]; } [customersTempList removeAllObjects]; } } please help me out of this, Thanks, Madan.

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  • Is it ok to use <strong> in place of <b> blindly ?

    - by metal-gear-solid
    Note: I know <b> is presentational and <span style="font-weight:bold> is better way and <strong> and <em> for emphasis but my question is not regarding this. Should we convert every <b> to <strong> blindly ? many people do this they think <b> is not good as per web standards so they convert every <b> to <strong> upon site redesign, content re-population, new site design and people suggest this to others also. Dreamweaver has also given option to convert all <b> and <i> to <strong> and <em> on code paste in design view and when we use B and I Which people use blindly. And Dreamweaver(if above option is checked) and many online WYSIWYG editor give output in <strong> and <em> while button shows B and I. In my opinion it's creating misconception about <strong> and <b> When we get content from client we don't know where client want to give emphasize and where he just want to use text bold for presentation purpose.What we should do in this condition? no one has time client and we both to give time to think for each bold text, it should be in <b> or in <strong>, <i> or in <em> What are pros and cons to convert every <b> and <i> into <strong> and <em> blindly if we are saying our site is accessible? Update: remember <b> and <i> are not deprecated there are in HTML 5 specification

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  • Building a QueryExpression where name field is either A or B

    - by Mike
    I'm trying to build a Dynamics CRM 4 query so that I can get calendar events that are named either "Event A" or "Event B". A QueryByAttribute doesn't seem to do the job as I cannot specify a condition where the field called "event_name" = "Event A" of "event_name" = "Event B". When using the QueryExpression, I've found the FilterExpression applies to the Referencing Entity. I don't know if the FilterExpression can be used on the Referenced Entity at all. The example below is something like what I want to achieve, though this would return an empty result set as it will go looking in the entity called "my_event_response" for a "name" attribute. It's starting to look like I will need to run several queries to get this but this is less efficient than if I can submit it all at once. ColumnSet columns = new ColumnSet(); columns.Attributes = new string[]{ "event_name", "eventid", "startdate", "city" }; ConditionExpression eventname1 = new ConditionExpression(); eventname1.AttributeName = "event_name"; eventname1.Operator = ConditionOperator.Equal; eventname1.Values = new string[] { "Event A" }; ConditionExpression eventname2 = new ConditionExpression(); eventname2.AttributeName = "event_name"; eventname2.Operator = ConditionOperator.Equal; eventname2.Values = new string[] { "Event B" }; FilterExpression filter = new FilterExpression(); filter.FilterOperator = LogicalOperator.Or; filter.Conditions = new ConditionExpression[] { eventname1, eventname2 }; LinkEntity link = new LinkEntity(); link.LinkCriteria = filter; link.LinkFromEntityName = "my_event"; link.LinkFromAttributeName = "eventid"; link.LinkToEntityName = "my_event_response"; link.LinkToAttributeName = "eventid"; QueryExpression query = new QueryExpression(); query.ColumnSet = columns; query.EntityName = EntityName.mbs_event.ToString(); query.LinkEntities = new LinkEntity[] { link }; RetrieveMultipleRequest request = new RetrieveMultipleRequest(); request.Query = query; return (RetrieveMultipleResponse)crmService.Execute(request); I'd appreciate some advice on how to get the data I need.

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  • How do I recover from an unchecked exception?

    - by erickson
    Unchecked exceptions are alright if you want to handle every failure the same way, for example by logging it and skipping to the next request, displaying a message to the user and handling the next event, etc. If this is my use case, all I have to do is catch some general exception type at a high level in my system, and handle everything the same way. But I want to recover from specific problems, and I'm not sure the best way to approach it with unchecked exceptions. Here is a concrete example. Suppose I have a web application, built using Struts2 and Hibernate. If an exception bubbles up to my "action", I log it, and display a pretty apology to the user. But one of the functions of my web application is creating new user accounts, that require a unique user name. If a user picks a name that already exists, Hibernate throws an org.hibernate.exception.ConstraintViolationException (an unchecked exception) down in the guts of my system. I'd really like to recover from this particular problem by asking the user to choose another user name, rather than giving them the same "we logged your problem but for now you're hosed" message. Here are a few points to consider: There a lot of people creating accounts simultaneously. I don't want to lock the whole user table between a "SELECT" to see if the name exists and an "INSERT" if it doesn't. In the case of relational databases, there might be some tricks to work around this, but what I'm really interested in is the general case where pre-checking for an exception won't work because of a fundamental race condition. Same thing could apply to looking for a file on the file system, etc. Given my CTO's propensity for drive-by management induced by reading technology columns in "Inc.", I need a layer of indirection around the persistence mechanism so that I can throw out Hibernate and use Kodo, or whatever, without changing anything except the lowest layer of persistence code. As a matter of fact, there are several such layers of abstraction in my system. How can I prevent them from leaking in spite of unchecked exceptions? One of the declaimed weaknesses of checked exceptions is having to "handle" them in every call on the stack—either by declaring that a calling method throws them, or by catching them and handling them. Handling them often means wrapping them in another checked exception of a type appropriate to the level of abstraction. So, for example, in checked-exception land, a file-system–based implementation of my UserRegistry might catch IOException, while a database implementation would catch SQLException, but both would throw a UserNotFoundException that hides the underlying implementation. How do I take advantage of unchecked exceptions, sparing myself of the burden of this wrapping at each layer, without leaking implementation details?

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  • Exception: attempt to acquire a reference on a close SQLiteClosable

    - by CommonsWare
    I posted this back in May on the [android-developers] Google Group. I never heard back and was not able to reproduce the problem until one of my students did last week. I figured I'd post it here and see if it rang any bells for anyone. In one of my code samples, I have the following method: static Cursor getAll(SQLiteDatabase db, String orderBy) { return(db.rawQuery("SELECT * FROM restaurants "+orderBy, null)); } When I run it, sporadically, I get this: 05-01 14:45:05.849: ERROR/AndroidRuntime(1145): java.lang.IllegalStateException: attempt to acquire a reference on a close SQLiteClosable 05-01 14:45:05.849: ERROR/AndroidRuntime(1145): at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:31) 05-01 14:45:05.849: ERROR/AndroidRuntime(1145): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:56) 05-01 14:45:05.849: ERROR/AndroidRuntime(1145): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:49) 05-01 14:45:05.849: ERROR/AndroidRuntime(1145): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:49) 05-01 14:45:05.849: ERROR/AndroidRuntime(1145): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1118) 05-01 14:45:05.849: ERROR/AndroidRuntime(1145): at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1092) 05-01 14:45:05.849: ERROR/AndroidRuntime(1145): at apt.tutorial.Restaurant.getAll(Restaurant.java:14) This makes no sense to me. The database is definitely open. The SQLiteClosable is the SQLiteQuery created by SQLiteQueryDriver, and I see no evidence that there is an object pool or something going on here that might explain how a "new" SQLiteClosable is already closed. The fact that it is sporadic (meaning the same UI operations sometimes trigger the exception, but not always) suggests some sort of pool, race condition, or something...but I'm not sure where. Thoughts? Thanks! UPDATE: The code in question is from the LunchList tutorials out of my Android Programming Tutorials book. It's a bit spread out and not terribly suitable for posting directly in SO. You can download the code for that book from the above link if you want to take a look at it. I do not recall exactly which edition of the tutorial the student was working on at the time, though it was in the Tutorial 12-Tutorial 16 range. I was mostly hoping to run across somebody who had tripped over this problem before and had a likely culprit. I'm fairly certain my database is open. Thanks again!

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  • deleting element objects of a std vector using erase : a) memory handling and b) better way?

    - by memC
    hi, I have a vec_A that stores instances of class A as: vec_A.push_back(A()); I want to remove some elements in the vector at a later stage and have two questions: a) The element is deleted as: vec_A.erase(iterator) Is there any additional code I need to add to make sure that there is no memory leak? . b) Assume that condition if(num <5) is if num is among a specific numberList. Given this, is there a better way to delete the elements of a vector than what I am illustrating below? #include<vector> #include<stdio.h> #include<iostream> class A { public: int getNumber(); A(int val); ~A(){}; private: int num; }; A::A(int val){ num = val; }; int A::getNumber(){ return num; }; int main(){ int i =0; int num; std::vector<A> vec_A; std::vector<A>::iterator iter; for ( i = 0; i < 10; i++){ vec_A.push_back(A(i)); } iter = vec_A.begin(); while(iter != vec_A.end()){ std::cout << "\n --------------------------"; std::cout << "\n Size before erase =" << vec_A.size(); num = iter->getNumber() ; std::cout << "\n num = "<<num; if (num < 5){ vec_A.erase(iter); } else{ iter++; } std::cout << "\n size after erase =" << vec_A.size(); } std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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  • Using Core Data Concurrently and Reliably

    - by John Topley
    I'm building my first iOS app, which in theory should be pretty straightforward but I'm having difficulty making it sufficiently bulletproof for me to feel confident submitting it to the App Store. Briefly, the main screen has a table view, upon selecting a row it segues to another table view that displays information relevant for the selected row in a master-detail fashion. The underlying data is retrieved as JSON data from a web service once a day and then cached in a Core Data store. The data previous to that day is deleted to stop the SQLite database file from growing indefinitely. All data persistence operations are performed using Core Data, with an NSFetchedResultsController underpinning the detail table view. The problem I am seeing is that if you switch quickly between the master and detail screens several times whilst fresh data is being retrieved, parsed and saved, the app freezes or crashes completely. There seems to be some sort of race condition, maybe due to Core Data importing data in the background whilst the main thread is trying to perform a fetch, but I'm speculating. I've had trouble capturing any meaningful crash information, usually it's a SIGSEGV deep in the Core Data stack. The table below shows the actual order of events that happen when the detail table view controller is loaded: Main Thread Background Thread viewDidLoad Get JSON data (using AFNetworking) Create child NSManagedObjectContext (MOC) Parse JSON data Insert managed objects in child MOC Save child MOC Post import completion notification Receive import completion notification Save parent MOC Perform fetch and reload table view Delete old managed objects in child MOC Save child MOC Post deletion completion notification Receive deletion completion notification Save parent MOC Once the AFNetworking completion block is triggered when the JSON data has arrived, a nested NSManagedObjectContext is created and passed to an "importer" object that parses the JSON data and saves the objects to the Core Data store. The importer executes using the new performBlock method introduced in iOS 5: NSManagedObjectContext *child = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType]; [child setParentContext:self.managedObjectContext]; [child performBlock:^{ // Create importer instance, passing it the child MOC... }]; The importer object observes its own MOC's NSManagedObjectContextDidSaveNotification and then posts its own notification which is observed by the detail table view controller. When this notification is posted the table view controller performs a save on its own (parent) MOC. I use the same basic pattern with a "deleter" object for deleting the old data after the new data for the day has been imported. This occurs asynchronously after the new data has been fetched by the fetched results controller and the detail table view has been reloaded. One thing I am not doing is observing any merge notifications or locking any of the managed object contexts or the persistent store coordinator. Is this something I should be doing? I'm a bit unsure how to architect this all correctly so would appreciate any advice.

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