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• Secondary keys in a B-tree

  - by Phenom

  Let's say that there is a file that contains an unsorted list of student information, which includes a student ID number as well as other information. I want to make a program that retrieves student information based on student ID number. In order to make it efficient, I store the student IDs in a B-tree. So when I enter a student ID number, it searches the B-tree to see if its there or not. It also does one more thing. If it finds the student ID number, then it also returns where in the file that student's information is. This is the secondary key. The program uses this information to locate the rest of the student's information and prints it to screen. Can this be done? Is this how a b-tree works?

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• aggregate over several variables in r

  - by Misha

  Dear overflowers, I have a rather large dataset in a long format where I need to count the number of instances of the ID due to two different variables, A & B. E.g. The same person can be represented in multiple rows due to either A or B. What I need to do is to count the number of instances of ID which is not too hard, but also count the number of ID due to A and B and return these as variables in the dataset. Regards, //Mi

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• Simple addition calculator in python

  - by Krysten

  I built a very simple addition calculator in python: #This program will add two numbers entered in by the user print "Welcome!" num1 = input("Please enter in the first number to be added.") num2 = input("Please enter in the second number to be added.") sum = num1 + num2 print "The sum of the two numbers entered is: ", sum I haven't setup python yet, so I'm using codepad.org (an online compiler). I get the following error: Welcome! Please enter in the first number to be addeded.Traceback (most recent call last): Line 5, in num1 = input("Please enter in the first number to be addeded.") EOFError

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• Scanning FedEx labels into a visual basic program

  - by 0bfus

  I have a program that has tracking numbers entered into it and it stores them in a database and i would like to add a scanner to the mix. The scanner is acting like a keyboard and scannes just fine, the problem is scanning a FedEx number gives a 32 digit number and i am only iterested in the tracking number portion of it. I saw an example on the web for an excel macro and tried to modify it but it doesnt seem to work. Is there something i could do to just get the 12 digit number? This is what it looks like so far. Any help would be greatly appreciated. With BarcodeText If .Text < "1z99999999999999999" Then .Text = Mid(.Text, 17, 12) End If

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• How to return something in Matlab?

  - by Ben Fossen

  I have a simple function function increase(percent, number) low = number- number*percent; end I want to return low so I can use it as an argument for another function mitoGen(asp, arg, increase(.2,234), glu) Is there a way to do this?

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• loop is cut one element of the array

  - by Walaa

  The problem is : Write a program that reads a number n and then declares an array of n elements. The program then fills the array with the first n numbers, where each number is two to the power of the previous. Finally, display array’s contents. My code : import java.util.*; public class Q1 { static Scanner scan = new Scanner (System.in); public static void main(String args [] ) { int num; int i = 0; System.out.println("Enter a number :"); num = scan.nextInt(); double [] a=new double[num]; a[0]= num ; for ( ;i<=a.length-1 ; i++) { a[i+1] = Math.pow(2,a[i]); System.out.println((int)(a[i]) ); } } } The error is : ----jGRASP exec: java Q1 Enter a number : 4 4 16 65536 Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4 at Q1.main(Q1.java:16) ----jGRASP wedge2: exit code for process is 1. why it says that? And the number by user printed twice!

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• Trying to boot from USB on Asus q200e-bhi3t45 just brings me to grub menu

  - by Krash Kharma

  It's been a struggle every time I've tried to change my OS on this machine. I honestly don't even know how it works whenever it does. I've somehow managed to get Windows 7, Windows 8, Mint 14, Ubuntu 12.04, and 12.10 to work at random times but it's always after struggling with it and googling for random chance fixes and suddenly something clicks and it loads from usb, but 99% of the time, every time I try to boot from USB to install a distro (in this case, I'm trying to get ubuntu-12.04.2-desktop-amd64.iso to work) my pc just comes up with a grub menu ("Minimal bash-like blahblahblah - grub ") I don't know why it works when it works. Right now I've tried everything from with/without Fast Boot in BIOS, with/without CSM, with/without secure boot, to changing BOOTx64.EFI to bootx64.efi to downloading a new bootx64.efi to copying it to every folder on the usb.... It makes no sense to me. Sorry if this has been asked before but I can't find anything

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• Java curious Loop Performance

  - by user1680583

  I have a big problem while evaluate my java code. To simplify the problem I wrote the following code which produce the same curious behavior. Important is the method run() and given double value rate. For my runtime test (in the main method) I set the rate to 0.5 one times and 1.0 the other time. With the value 1.0 the if-statement will be executed in each loop iteration and with the value 0.5 the if-statement will be executed half as much. For this reason I expected longer runtime by the first case but opposite is true. Can anybody explain me this phenomenon?? The result of main: Test mit rate = 0.5 Length: 50000000, IF executions: 25000856 Execution time was 4329 ms. Length: 50000000, IF executions: 24999141 Execution time was 4307 ms. Length: 50000000, IF executions: 25001582 Execution time was 4223 ms. Length: 50000000, IF executions: 25000694 Execution time was 4328 ms. Length: 50000000, IF executions: 25004766 Execution time was 4346 ms. ================================= Test mit rate = 1.0 Length: 50000000, IF executions: 50000000 Execution time was 3482 ms. Length: 50000000, IF executions: 50000000 Execution time was 3572 ms. Length: 50000000, IF executions: 50000000 Execution time was 3529 ms. Length: 50000000, IF executions: 50000000 Execution time was 3479 ms. Length: 50000000, IF executions: 50000000 Execution time was 3473 ms. The Code public ArrayList<Byte> list = new ArrayList<Byte>(); public final int LENGTH = 50000000; public PerformanceTest(){ byte[]arr = new byte[LENGTH]; Random random = new Random(); random.nextBytes(arr); for(byte b : arr) list.add(b); } public void run(double rate){ byte b = 0; int count = 0; for (int i = 0; i < LENGTH; i++) { if(getRate(rate)){ list.set(i, b); count++; } } System.out.println("Length: " + LENGTH + ", IF executions: " + count); } public boolean getRate(double rate){ return Math.random() < rate; } public static void main(String[] args) throws InterruptedException { PerformanceTest test = new PerformanceTest(); long start, end; System.out.println("Test mit rate = 0.5"); for (int i = 0; i < 5; i++) { start=System.currentTimeMillis(); test.run(0.5); end = System.currentTimeMillis(); System.out.println("Execution time was "+(end-start)+" ms."); Thread.sleep(500); } System.out.println("================================="); System.out.println("Test mit rate = 1.0"); for (int i = 0; i < 5; i++) { start=System.currentTimeMillis(); test.run(1.0); end = System.currentTimeMillis(); System.out.println("Execution time was "+(end-start)+" ms."); Thread.sleep(500); } }

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• Playing audio files from system directory

  - by zx

  hi, I have audio files in var/ This is the file name 2-3109999999-3246758493-1271129518-1271129505.6.wav Format 2=campaign id 3109999999=caller id 3246758493=number called 1271129518=timestamp call ended 1271129505=timestamp call started 6=call id If I were to pass just the number called which was 3246758493, how can I find all the files without defining all the other variables(such as timestamp, etc) and just the files that have that number in the filename?

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• reverse a linked list?

  - by sil3nt

  Hi there, Im trying to reverse the order of the following linked list, I've done so, But the reversed list does not seem to print out. Where have I gone wrong? //reverse the linked list #include <iostream> using namespace std; struct node{ int number; node *next; }; node *A; void addNode(node *&listpointer, int num){ node *temp; temp = new node; temp->number = num; temp->next = listpointer; listpointer = temp; } void reverseNode(node *&listpointer){ node *temp,*current; current = listpointer; temp = new node; while (true){ if (current == NULL){ temp = NULL; break; } temp->number = current->number; current = current->next; temp = temp->next; } listpointer = temp; } int main(){ A = NULL; addNode(A,1); addNode(A,2); addNode(A,3); while (true){ if (A == NULL){break;} cout<< A->number << endl; A = A->next; } cout<< "****" << endl; reverseNode(A); while (true){ if (A == NULL){break;} cout<< A->number << endl; A = A->next; } cout<< "****"<< endl; return 0; }

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• Actionscript - Dropping Multiple Objects Using an Array?

  - by Eratosthenes

  I'm trying to get these fireBalls to drop more often, im not sure if im using Math.random correctly also, for some reason I'm getting a null reference because I think the fireBalls array waits for one to leave the stage before dropping another one? this is the relevant code: var sun:Sun=new Sun var fireBalls:Array=new Array() var left:Boolean; function onEnterFrame(event:Event){ if (left) { sun.x = sun.x - 15; }else{ sun.x = sun.x + 15; } if (fireBalls.length>0&&fireBalls[0].y>stage.stageHeight){ // Fireballs exit stage removeChild(fireBalls[0]); fireBalls.shift(); } for (var j:int=0; j<fireBalls.length; j++){ fireBalls[j].y=fireBalls[j].y+15; if (fireBalls[j].y>stage.stageHeight-fireBall.width/2){ } } if (Math.random()<.2){ // Fireballs shooting from Sun var fireBall:FireBall=new FireBall; fireBall.x=sun.x; addChild(fireBall); fireBalls.push(fireBall); } }

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• trying to put an mysql result into a string

  - by user1583432

  I'm trying to put an mysql query result into an string I tried to find an answer but all the similar posts were getting subquery answers which is not what I'm trying to do. for example Fruits_tbl ID Fruit Color Number __________________________________ 2 Apple Red 5 $sql = "select Fruits,Color,Number from Fruits_tbl where ID = 2"; $result = $pdo->query($sql); $row = $result->fetch(); print_r($row); This will give me something like Array([0]="Apple", [1]="Red", [2]="5", [Fruit]="Apple", [Color]="Red", [Number]="5") implode will give me 2 of each I want just need a string = "Apple, Red, 5" what I currently have is $string = $row[Fruit].", ".$row[Color].", ".$row['Number'] As you can see that's rather tedious. Is there something like implode but only return the index array or something?

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• Error while converting function from oracle to SQL Server

  - by sss

  Hi, I am migrating a function from Oracle to SQL Server 2008. This function raises SELECT statements included within a function cannot return data to a client as error. How can I solve this problem? Original PLSQL Code CREATE OR REPLACE function f_birim_cevrim_katsayi (p_ID_MAMUL in number, p_ID_BIRIMDEN in number, p_ID_BIRIME in number) return number is v_katsayi number; begin v_katsayi:=0; if p_ID_BIRIMDEN!=p_ID_BIRIME then for c in ( select * from CR_BIRIM_CEVRIM where ID_MAMUL = p_ID_MAMUL and ( (ID_BIRIM = p_ID_BIRIMDEN and ID_BIRIM2 = p_ID_BIRIME) OR ( ID_BIRIM2 = p_ID_BIRIMDEN and ID_BIRIM = p_ID_BIRIME) ) and VALID = 1) loop if c.ID_BIRIM=p_ID_BIRIMDEN then v_katsayi:=c.MT_ORAN; else v_katsayi:=1/c.MT_ORAN; end if; end loop; else v_katsayi:=1; end if; return round(v_katsayi,10); exception when others then return 0; end; T-SQL code: If Exists ( SELECT name FROM sysobjects WHERE name = 'f_birim_cevrim_katsayi' AND type = 'FN') DROP FUNCTION f_birim_cevrim_katsayi GO CREATE FUNCTION f_birim_cevrim_katsayi ( @p_ID_MAMUL FLOAT , @p_ID_BIRIMDEN FLOAT , @p_ID_BIRIME FLOAT ) RETURNS float AS BEGIN DECLARE @adv_error INT DECLARE @v_katsayi FLOAT SELECT @v_katsayi = 0 IF @p_ID_BIRIMDEN != @p_ID_BIRIME BEGIN DECLARE cursor_for_inline_select1 CURSOR LOCAL FOR SELECT * FROM CR_BIRIM_CEVRIM WHERE ID_MAMUL = @p_ID_MAMUL AND ((ID_BIRIM = @p_ID_BIRIMDEN AND ID_BIRIM2 = @p_ID_BIRIME) OR (ID_BIRIM2 = @p_ID_BIRIMDEN AND ID_BIRIM = @p_ID_BIRIME)) AND VALID = 1 OPEN cursor_for_inline_select1 FETCH NEXT FROM cursor_for_inline_select1 WHILE (@@FETCH_STATUS <> -1) BEGIN IF c.ID_BIRIM = @p_ID_BIRIMDEN BEGIN SELECT @v_katsayi = c.MT_ORAN END ELSE BEGIN SELECT @v_katsayi = 1/c.MT_ORAN END END CLOSE cursor_for_inline_select1 DEALLOCATE cursor_for_inline_select1 END ELSE BEGIN SELECT @v_katsayi = 1 END DEALLOCATE cursor_for_inline_select1 return ROUND(@v_katsayi, 10) GOTO ExitLabel1 Exception1: BEGIN DEALLOCATE cursor_for_inline_select1 return 0 END ExitLabel1: return ROUND(@v_katsayi, 10) END GO

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• Problem with reading and writing to binary file in C++

  - by Reem

  I need to make a file that contains "name" which is a string -array of char- and "data" which is array of bytes -array of char in C++- but the first problem I faced is how to separate the "name" from the "data"? newline character could work in this case (assuming that I don't have "\n" in the name) but I could have special characters in the "data" part so there's no way to know when it ends so I'm putting an int value in the file before the data which has the size of the "data"! I tried to do this with code as follow: if((fp = fopen("file.bin","wb")) == NULL) { return false; } char buffer[] = "first data\n"; fwrite( buffer ,1,sizeof(buffer),fp ); int number[1]; number[0]=10; fwrite( number ,1,1, fp ); char data[] = "1234567890"; fwrite( data , 1, number[0], fp ); fclose(fp); but I didn't know if the "int" part was right, so I tried many other codes including this one: char buffer[] = "first data\n"; fwrite( buffer ,1,sizeof(buffer),fp ); int size=10; fwrite( &size ,sizeof size,1, fp ); char data[] = "1234567890"; fwrite( data , 1, number[0], fp ); I see 4 "NULL" characters in the file when I open it instead of seeing an integer. Is that normal? The other problem I'm facing is reading that again from the file! The code I tried to read didn't work at all :( I tried it with "fread" but I'm not sure if I should use "fseek" with it or it just read the other character after it. Forgive me but I'm a beginner :(

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• Is my program taking too much time to execute?

  - by Conrad C

  I wanted to solve a question from project euleur about finding the largest prime number of a big number. I run my code on a virtual machine on Visual studio 2012, and the code seems froze. When I step into the loop, the code works well, but when I execute it, the console is always there. It is as if the program is still running. Could it be that the program takes time to execute? My Code static void Main(string[] args) { long number = 5; for (long i = 1; i < 600851475143; i++) { if (i % 2 != 0 && i % 1 == 0 && i % i == 0) number = i; } }

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• preg_replace - don't include string if $4 is blank

  - by bradenkeith

  I have this expression: $regex_phone = '/^(?:1(?:[. -])?)?(?:\((?=\d{3}\)))?([2-9]\d{2})' .'(?:(?<=\(\d{3})\))? ?(?:(?<=\d{3})[.-])?([2-9]\d{2})' .'[. -]?(\d{4})(?: (?i:ext)\.? ?(\d{1,5}))?$/'; if(!preg_match($regex_phone, $data['phone'])){ $error[] = "Please enter a valid phone number."; }else{ $data['phone'] = preg_replace($regex_phone, '($1) $2-$3 ext.$4', $data['phone']); } That will take a phone number such as: 803-888-8888 ext 2 as well as 803-888-8888 First number formats as: (803) 888-8888 ext.2 -- the desired effect Second number formats as: (803) 888-8888 ext. -- blank extension How can I set it so that if $4 is blank, that ext. won't show? Thanks so much for any help you can offer. I hope this was clear.

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• Make function declarations based on function definitions

  - by Clinton Blackmore

  I've written a .cpp file with a number of functions in it, and now need to declare them in the header file. It occurred to me that I could grep the file for the class name, and get the declarations that way, and it would've worked well enough, too, had the complete function declaration before the definition -- return code, name, and parameters (but not function body) -- been on one line. It seems to me that this is something that would be generally useful, and must've been solved a number of times. I am happy to edit the output and not worried about edge cases; anything that gives me results that are right 95% of the time would be great. So, if, for example, my .cpp file had: i2cstatus_t NXTI2CDevice::writeRegisters( uint8_t start_register, // start of the register range uint8_t bytes_to_write, // number of bytes to write uint8_t* buffer = 0) // optional user-supplied buffer { ... } and a number of other similar functions, getting this back: i2cstatus_t NXTI2CDevice::writeRegisters( uint8_t start_register, // start of the register range uint8_t bytes_to_write, // number of bytes to write uint8_t* buffer = 0) for inclusion in the header file, after a little editing, would be fine. Getting this back: i2cstatus_t writeRegisters( uint8_t start_register, uint8_t bytes_to_write, uint8_t* buffer); or this: i2cstatus_t writeRegisters(uint8_t start_register, uint8_t bytes_to_write, uint8_t* buffer); would be even better.

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• PHP - Open or copy a file when knowing only part of its name?

  - by Gary Willoughby

  I have a huge repository of files that are ordered by numbered folders. In each folder is a file which starts with a unique number then an unknown string of characters. Given the unique number how can i open or copy this file? for example: I have been given the number '7656875' and nothing more. I need to interact with a file called '\server\7656800\7656875 foobar 2x4'. how can i achieve this using PHP?

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• Create unique identifier for different row-groups

  - by Max van der Heijden

  I want to number certain combinations of row in a dataframe (which is ordered on ID and on Time) tc <- textConnection(' id time end_yn number abc 10 0 1 abc 11 0 2 abc 12 1 3 abc 13 0 1 def 10 0 1 def 15 1 2 def 16 0 1 def 17 0 2 def 18 1 3 ') test <- read.table(tc, header=TRUE) The goal is to create a new column ("journey_nr") that give a unique number to each row based on the journey it belongs to. Journeys are defined as a sequence of rows per id up until to end_yn == 1, also if end_ynnever becomes 1, the journey should also be numbered (see the expected outcome example). It is only possible to have end_yn == 0 journeys at the end of a collection of rows for an ID (as shown at row 4 for id 3). So either no end_yn == 1 has occured for that ID or that happened before the end_yn == 0-journey (see id == abc in the example). I know how to number using the data.table package, but I do not know which columns to combine in order to get the expected outcome. I've searched the data.table-tag on SO, but could not find a similar problem. Expected outcome: id time end_yn number journey abc 10 0 1 1 abc 11 0 2 1 abc 12 1 3 1 abc 13 0 1 2 def 10 0 1 3 def 15 1 2 3 def 16 0 1 4 def 17 0 2 4 def 18 1 3 4

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• How to implement a FIFO listcontrol in MFC ?

  - by srimal

  I need to implement a list control using MFC with the number of lines being fixed. It should Use FIFO with the number of lines being a fixed number. Is there an inbuilt option to this? Or a programmable method.

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• regular expresson of variables

  - by Kevinniceguy

  what is re of string of 0 and 1 that contain an even number of zeros and even number of ones..... its not or in the middle....its an and...and even number of ones so i got something like (1*01*01*)*(0*10*10*)* does it look good?

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• Defining and using controller methods in ember.js

  - by OriginalEXE

  first of all, I am total noob when it comes to OOP in JS, this is new to me so treat me like a noob. I am building my first ember.js application and I am stuck (not the first time but I would get unstuck by myself, this is a tough one though). I have two models: forms entries Entries is of course in (one to many) relationship to forms, so each form can have as many properties. Form properties: id : DS.attr( 'number' ), title : DS.attr( 'string' ), views : DS.attr( 'number' ), conversion : DS.attr( 'number' ), entries : DS.hasMany( 'entry' ) Entry properties: id : DS.attr( 'number' ), parent_id: DS.belongsTo( 'form' ) Now, I have forms route that displays all forms in tabled view, and each table row has some info like form id, name etc. and that works great. What I wanted to do is display the number of entries each form has. I figured I should do that via controller, so here is my controller now: // Form controller App.FormController = Ember.ObjectController.extend({ entriescount: function() { var entries = this.get( 'store').find( 'entry' ); return entries.filterBy( 'parent_id', this.get( 'id' ) ).get( 'length' ); }.property( '[email protected]_id') }); Now for some reason, when I use {{entriescount}} in {{#each}} loop, this returns nothing. It also returns nothing in single form route. Note that in both cases, {{title}} for example works. I am wondering, am I going the right way by using controller for this, and how do I get controller to output the data. Thanks

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• Counting XML elements in file on Android

  - by CSharperWithJava

  Take a simple XML file formatted like this: <Lists> <List> <Note/> ... <Note/> </List> <List> <Note/> ... <Note/> </List> </Lists> Each node has some attributes that actually hold the data of the file. I need a very quick way to count the number of each type of element, (List and Note). Lists is simply the root and doesn't matter. I can do this with a simple string search or something similar, but I need to make this as fast as possible. Design Parameters: Must be in java (Android application). Must AVOID allocating memory as much as possible. Must return the total number of Note elements and the number of List elements in the file, regardless of location in file. Number of Lists will typically be small (1-4), and number of notes can potentially be very large (upwards of 1000, typically 100) per file. I look forward to your suggestions.

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• Mysql - Rank field for a query

  - by Mark

  How can I add a field that contains a rows rank within the result set of a query? Initially I used php to rank my results as it was all on a single page. Now I have added multiple pages so now even though I am on the second page the first result on the page is still '1st'. Obviously I could multiply the page number by the number of results per page and add the result number but I imagine there is a better way within the query. Thanks,

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• Generate (in R) a matrix of all possible outcomes for throwing n dice (ignoring order)

  - by Brani

  In cases where order does matter, it's rather easy to generate the matrix of all possible outcomes. One way for doing this is using expand.grid as shown here. What if it doesn't? If I'm right, the number of possible combinations is (S+N-1)!/S!(N-1)!, where S is the number of dice, each with N sides numbered 1 through N. (It is different from the well known combinations formula because it is possible for the same number to appear on more than one dice). For example, when throwing four six-sided dice, N=6 and S=4, so the number of possible combinations is (4+6-1)!/4!(6-1)! = 9!/4!x5! = 126. How can I generate a matrix of these 126 possible outcomes? Thank you.

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