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  • Trapping messages in .NET

    - by user350632
    How can i trap a Windows system message (like WM_SETTEXT) that was sent by some window (VLC player window in my case)? I've tried to inherit NativeWindow class and override WndProc like this: class VLCFilter : NativeWindow { System.IntPtr iHandle; const int WM_SETTEXT = 0x000C; public VLCFilter() { Process p = Process.GetProcessesByName("vlc")[0]; iHandle = p.MainWindowHandle; } protected override void WndProc(ref Message aMessage) { base.WndProc(ref aMessage); if (aMessage.HWnd != iHandle) return false; if (aMessage.Msg == WM_SETTEXT) { MessageBox.Show("VLC window text changed!"); } } } I have checked with Microsoft Spy++ that WM_SETTEXT message is sent by VLC player but my code doesn't seem to get the work done. I've refered mainly to: http://www.codeproject.com/kb/dotnet/devicevolumemonitor.aspx I'm trying to make this work for some time with no success. What am I doing wrong? What I am not doing? Maybe there is easier way to do this? My initial goal is to catch when VLC player (that could be playing somewhere in the background and is not emmbed in my application) repeats its playback (have noticed that WM_SETTEXT message is sent then and I'm trying to find it out like this).

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  • Changing type of object in a conditional

    - by David Doria
    I'm having a bit of trouble with dynamic_casting. I need to determine at runtime the type of an object. Here is a demo: include include class PersonClass { public: std::string Name; virtual void test(){}; //it is annoying that this has to be here... }; class LawyerClass : public PersonClass { public: void GoToCourt(){}; }; class DoctorClass : public PersonClass { public: void GoToSurgery(){}; }; int main(int argc, char *argv[]) { PersonClass* person = new PersonClass; if(true) { person = dynamic_cast(person); } else { person = dynamic_cast(person); } person-GoToCourt(); return 0; } I would like to do the above. The only legal way I found to do it is to define all of the objects before hand: PersonClass* person = new PersonClass; LawyerClass* lawyer; DoctorClass* doctor; if(true) { lawyer = dynamic_cast(person); } else { doctor = dynamic_cast(person); } if(true) { lawyer-GoToCourt(); } The main problem with this (besides having to define a bunch of objects that won't be use) is that I have to change the name of the 'person' variable. Is there a better way? (I am not allowed to change any of the classes (Person, Lawyer, or Doctor) because they are part of a library that people who will use my code have and won't want to change). Thanks, Dave

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  • How to optimize paging for large in memory database

    - by snakefoot
    I have an application where the entire database is implemented in memory using a stl-map for each table in the database. Each item in the stl-map is a complex object with references to other items in the other stl-maps. The application works with a large amount of data, so it uses more than 500 MByte RAM. Clients are able to contact the application and get a filtered version of the entire database. This is done by running through the entire database, and finding items relevant for the client. When the application have been running for an hour or so, then Windows 2003 SP2 starts to page out parts of the RAM for the application (Eventhough there is 16 GByte RAM on the machine). After the application have been partly paged out then a client logon takes a long time (10 mins) because it now generates a page fault for each pointer lookup in the stl-map. I can see it is possible to tell Windows to lock memory in RAM, but this is generally only recommended for device drivers, and only for "small" amounts of memory. I guess a poor mans solution could be to loop through the entire memory database, and thus tell Windows we are still interested in keeping the datamodel in RAM. I guess another poor mans solution could be to disable the pagefile completely on Windows. I guess the expensive solution would be a SQL database, and then rewrite the entire application to use a database layer. Then hopefully the database system will have implemented means to for fast access. Are there other more elegant solutions ?

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  • Issue selenium code maintenance

    - by Rajasankar
    I want to group the common methods in one file and use it. For example, login to a page using selenium may be used in multiple times. Define that in class A and call it in class B. However, it throws null pointer exception. class A has public void test_Login() throws Exception { try{ selenium.setTimeout("60000"); selenium.open("http://localhost"); selenium.windowFocus(); selenium.windowMaximize(); selenium.windowFocus(); selenium.type("userName", "admin"); selenium.type("password", "admin"); Result=selenium.isElementPresent("//input[@type='image']"); selenium.click("//input[@type='image']"); selenium.waitForPageToLoad(Timeout); } catch(Exception ex) { System.out.println(ex); ex.printStackTrace(); } } with all other java syntax in class B public void test_kk() throws Exception { try { a.test_Login(); } catch(Exception ex) { System.out.println(ex); ex.printStackTrace(); } } with all syntax. When I execute class B, I got this error, java.lang.NullPointerException at A.test_Login(A.java:32) at B.test_kk(savefile.java:58) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at com.thoughtworks.selenium.SeleneseTestCase.runBare(SeleneseTestCase.j ava:212) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:232) at junit.framework.TestSuite.run(TestSuite.java:227) at junit.textui.TestRunner.doRun(TestRunner.java:116) at junit.textui.TestRunner.doRun(TestRunner.java:109) at junit.textui.TestRunner.run(TestRunner.java:77) at B.main(B.java:77) I hope someone must have tried this before. I may miss something here.

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  • How is the C++ synthesized move constructor affected by volatile and virtual members?

    - by user1827766
    Look at the following code: struct node { node(); //node(const node&); //#1 //node(node&&); //#2 virtual //#3 ~node (); node* volatile //#4 next; }; main() { node m(node()); //#5 node n=node(); //#6 } When compiled with gcc-4.6.1 it produces the following error: g++ -g --std=c++0x -c -o node.o node.cc node.cc: In constructor node::node(node&&): node.cc:3:8: error: expression node::next has side-effects node.cc: In function int main(): node.cc:18:14: note: synthesized method node::node(node&&) first required here As I understand the compiler fails to create default move or copy constructor on line #6, if I uncomment either line #1 or #2 it compiles fine, that is clear. The code compiles fine without c++0x option, so the error is related to default move constructor. However, what in the node class prevents default move constructor to be created? If I comment any of the lines #3 or #4 (i.e. make the destructor non-virtual or make data member non-volatile) it compiles again, so is it the combination of these two makes it not to compile? Another puzzle, line #5 does not cause an compilation error, what is different from line #6? Is it all specific for gcc? or gcc-4.6.1?

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  • Pointers and Addresses in C

    - by Mohit
    #include "stdio.h" main() { int i=3,*x; float j=1.5,*y; char k='c',*z; x=&i; y=&j; z=&k; printf("\nAddress of x= %u",x); printf("\nAddress of y= %u",y); printf("\nAddress of z= %u",z); x++; y++;y++;y++;y++; z++; printf("\nNew Address of x= %u",x); printf("\nNew Address of y= %u",y); printf("\nNew Address of z= %u",z); printf("\nNew Value of i= %d",i); printf("\nNew Value of j= %f",j); printf("\nNew Value of k= %c\n",k); } Output: Address of x= 3219901868 Address of y= 3219901860 Address of z= 3219901875 New Address of x= 3219901872 New Address of y= 3219901876 New Address of z= 3219901876 New Value of i= 3 New Value of j= 1.500000 New Value of k= c The new address of variable y and z are same. How can two variables have same address and et have different values? Note: I used gcc compiler on Ubuntu 9.04

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  • Measuring the CPU frequency scaling effect

    - by Bryan Fok
    Recently I am trying to measure the effect of the cpu scaling. Is it accurate if I use this clock to measure it? template<std::intmax_t clock_freq> struct rdtsc_clock { typedef unsigned long long rep; typedef std::ratio<1, clock_freq> period; typedef std::chrono::duration<rep, period> duration; typedef std::chrono::time_point<rdtsc_clock> time_point; static const bool is_steady = true; static time_point now() noexcept { unsigned lo, hi; asm volatile("rdtsc" : "=a" (lo), "=d" (hi)); return time_point(duration(static_cast<rep>(hi) << 32 | lo)); } }; Update: According to the comment from my another post, I believe redtsc cannot use for measure the effect of cpu frequency scaling because the counter from the redtsc does not affected by the CPU frequency, am i right?

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  • Better language or checking tool?

    - by rwallace
    This is primarily aimed at programmers who use unmanaged languages like C and C++ in preference to managed languages, forgoing some forms of error checking to obtain benefits like the ability to work in extremely resource constrained systems or the last increment of performance, though I would also be interested in answers from those who use managed languages. Which of the following would be of most value? A language that would optionally compile to CLR byte code or to machine code via C, and would provide things like optional array bounds checking, more support for memory management in environments where you can't use garbage collection, and faster compile times than typical C++ projects. (Think e.g. Ada or Eiffel with Python syntax.) A tool that would take existing C code and perform static analysis to look for things like potential null pointer dereferences and array overflows. (Think e.g. an open source equivalent to Coverity.) Something else I haven't thought of. Or put another way, when you're using C family languages, is the top of your wish list more expressiveness, better error checking or something else? The reason I'm asking is that I have a design and prototype parser for #1, and an outline design for #2, and I'm wondering which would be the better use of resources to work on after my current project is up and running; but I think the answers may be useful for other tools programmers also. (As usual with questions of this nature, if the answer you would give is already there, please upvote it.)

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  • C struct written in file, open with Java

    - by DaunnC
    For example in C I have structure: typedef struct { int number; double x1; double y1; double x2; double y2; double x3; double y3; } CTRstruct;` Then I write it to file fwrite(&tr, 1, sizeof(tr), fp); (tr - its CTRstruct var, fp - File pointer); Then I need to read it with Java! I really don't know how to read struct from file... I tried to read it with ObjectInputStream(), last idea is to read with RandomAccessFile() but I also don't know how to... (readLong(), readDouble() also doesn't work, it works ofcource but doesn't read correct data). So, any idea how to read C struct from binary file with Java? If it's interesting, my version to read integer (but it's ugly, & I don't know what to do with double): public class MyDataInputStream extends DataInputStream{ public MyDataInputStream(InputStream AIs) { super(AIs); } public int readInt1() throws IOException{ int ch1 = in.read(); int ch2 = in.read(); int ch3 = in.read(); int ch4 = in.read(); if ((ch1 | ch2 | ch3 | ch4) < 0) throw new EOFException(); return ((ch4 << 24) + (ch3 << 16) + (ch2 << 8) + (ch1 << 0)); } with double we can deal the same way (like with int or with long (8bytes) & then convert to double with native func).

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  • StringBufferInputStream Question in Java

    - by JJG
    I want to read an input string and return it as a UTF8 encoded string. SO I found an example on the Oracle/Sun website that used FileInputStream. I didn't want to read a file, but a string, so I changed it to StringBufferInputStream and used the code below. The method parameter jtext, is some Japanese text. Actually this method works great. The question is about the deprecated code. I had to put @SuppressWarnings because StringBufferInputStream is deprecated. I want to know is there a better way to get a string input stream? Is it ok just to leave it as is? I've spent so long trying to fix this problem that I don't want to change anything now I seem to have cracked it. @SuppressWarnings("deprecation") private String readInput(String jtext) { StringBuffer buffer = new StringBuffer(); try { StringBufferInputStream sbis = new StringBufferInputStream (jtext); InputStreamReader isr = new InputStreamReader(sbis, "UTF8"); Reader in = new BufferedReader(isr); int ch; while ((ch = in.read()) > -1) { buffer.append((char)ch); } in.close(); return buffer.toString(); } catch (IOException e) { e.printStackTrace(); return null; } }

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  • SWIG_NewPointerObj and values always being nil

    - by Tom J Nowell
    I'm using SWIG to wrap C++ objects for use in lua, and Im trying to pass data to a method in my lua script, but it always comes out as 'nil' void CTestAI::UnitCreated(IUnit* unit){ lua_getglobal(L, "ai"); lua_getfield(L, -1, "UnitCreated"); swig_module_info *module = SWIG_GetModule( L ); swig_type_info *type = SWIG_TypeQueryModule( module, module, "IUnit *" ); SWIG_NewPointerObj(L,unit,type,0); lua_epcall(L, 1, 0); } Here is the lua code: function AI:UnitCreated(unit) if(unit == nil) then game:SendToConsole("I CAN HAS nil ?") else game:SendToConsole("I CAN HAS UNITS!!!?") end end unit is always nil. I have checked and in the C++ code, the unit pointer is never invalid/null I've also tried: void CTestAI::UnitCreated(IUnit* unit){ lua_getglobal(L, "ai"); lua_getfield(L, -1, "UnitCreated"); SWIG_NewPointerObj(L,unit,SWIGTYPE_p_IUnit,0); lua_epcall(L, 1, 0); } with identical results. Why is this failing? How do I fix it?

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  • jQuery: If user clicks out of div

    - by Paul Knopf
    I am creating a popup in query. All is well with the popup on hover. I made it see a timer starts when user's mouse leaves the div to close it. If he enters the div again before the timer is done, then the timer is cleared. This is fine, but what if a user clicks out of the div? I want that to also close the div. The only problem is that I don't want to attach click events to the wrapper on the page (because it includes the popout menu). I have seen techniques that wraps entire screen with a transparent div, and then attach a click event to hit. Although this may work, it confuses the user if he clicks the hidden div intending to click a link. He will have to click the link twice. Once two close the div (hiding the link), and another time to actually click think. Also, you loose in mouse cursors attached to any masked elements on the page (such as links cursor pointer, etc). There has to be a way to check if the user clicked out of the div without a modal and without attaching events to the entire page (page wrappers and child elements included). onclicksomewhereelse="closeme();" lol.

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  • Obtaining command line arguments in a QT application

    - by morpheous
    The following snippet is from a little app I wrote using the QT framework. The idea is that the app can be run in batch mode (i.e. called by a script) or can be run interactively. It is important therefore, that I am able to parse command line arguments in order to know which mode in which to run etc. [Edit] I am debugging using QTCreator 1.3.1 on Ubuntu Karmic. The arguments are passed in the normal way (i.e. by adding them via the 'Project' settings in the QTCreator IDE). When I run the app, it appears that the arguments are not being passed to the application. The code below, is a snippet of my main() function. int main(int argc, char *argv[]) { //Q_INIT_RESOURCE(application); try { QApplication the_app(argc, argv); //trying to get the arguments into a list QStringList cmdline_args = QCoreApplication::arguments(); // Code continues ... } catch (const MyCustomException &e) { return 1; } return 0; } [Update] I have identified the problem - for some reason, although argc is correct, the elements of argv are empty strings. I put this little code snippet to print out the argv items - and was horrified to see that they were all empty. for (int i=0; i< argc; i++){ std::string s(argv[i]); //required so I can see the damn variable in the debugger std::cout << s << std::endl; } Does anyone know what on earth is going on (or a hammer)?

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  • an algorhithm for filtering out raw txt files

    - by Roman Luštrik
    Imagine you have a .txt file of the following structure: >>> header >>> header >>> header K L M 200 0.1 1 201 0.8 1 202 0.01 3 ... 800 0.4 2 >>> end of file 50 0.1 1 75 0.78 5 ... I would like to read all the data except lines denoted by >>> and lines below the >>> end of file line. So far I've solved this using read.table(comment.char = ">", skip = x, nrow = y) (x and y are currently fixed). This reads the data between the header and >>> end of file. However, I would like to make my function a bit more plastic regarding the number of rows. Data may have values larger than 800, and consequently more rows. I could scan or readLines the file and see which row corresponds to the >>> end of file and calculate the number of lines to be read. What approach would you use?

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  • C++, generic programming and virtual functions. How do I get what I want?

    - by carleeto
    This is what I would like to do using templates: struct op1 { virtual void Method1() = 0; } ... struct opN { virtual void MethodN() = 0; } struct test : op1, op2, op3, op4 { virtual void Method1(){/*do work1*/}; virtual void Method2(){/*do work2*/}; virtual void Method3(){/*do work3*/}; virtual void Method4(){/*do work4*/}; } I would like to have a class that simply derives from a template class that provides these method declarations while at the same time making them virtual. This is what I've managed to come up with: #include <iostream> template< size_t N > struct ops : ops< N - 1 > { protected: virtual void DoStuff(){ std::cout<<N<<std::endl; }; public: template< size_t i > void Method() { if( i < N ) ops<i>::DoStuff(); } //leaving out compile time asserts for brevity } struct test : ops<6> { }; int main( int argc, char ** argv ) { test obj; obj.Method<3>(); //prints 3 return 0; } However, as you've probably guessed, I am unable to override any of the 6 methods I have inherited. I'm obviously missing something here. What is my error? No, this isn't homework. This is curiosity.

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  • Simple C++ code (what's wrong here?)

    - by JW
    Noob to C++. I'm trying to get user input (Last Name, First Name Middle Name), change part of it (Middle Name to Middle Initial) and then rearrange it (First Middle Initial Last). Where am I messing up in my code? --Thanks for ANY help you can offer! ... #include <iostream> using std::cout; using std::cin; #include <string> using std::string; int main() { string myString, last, first, middle; cout << "Enter your name: Last, First Middle"; cin >> last >> first >> middle; char comma, space1, space2; comma = myString.find_first_of(','); space1 = myString.find_first_of(' '); space2 = myString.find_last_of(' '); last = myString.substr (0, comma); // user input last name first = myString.substr (space1+1, -1); // user input first name middle = myString.substr (space2+1, -1); // user input middle name middle.insert (0, space2+1); // inserts middle initial in front of middle name middle.erase (1, -1); // deletes full middle name, leaving only middle initial myString = first + ' ' + middle + ' ' + last; // return 0; }

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  • Checking if a function has C-linkage at compile-time

    - by scjohnno
    Is there any way to check if a given function is declared with C-linkage (that is, with extern "C") at compile-time? I am developing a plugin system. Each plugin can supply factory functions to the plugin-loading code. However, this has to be done via name (and subsequent use of GetProcAddress or dlsym). This requires that the functions be declared with C-linkage so as to prevent name-mangling. It would be nice to be able to throw a compiler error if the referred-to function is declared with C++-linkage (as opposed to finding out at runtime when a function with that name does not exist). Here's a simplified example of what I mean: extern "C" void my_func() { } void my_other_func() { } // Replace this struct with one that actually works template<typename T> struct is_c_linkage { static const bool value = true; }; template<typename T> void assertCLinkage(T *func) { static_assert(is_c_linkage<T>::value, "Supplied function does not have C-linkage"); } int main() { assertCLinkage(my_func); // Should compile assertCLinkage(my_other_func); // Should NOT compile } Thanks.

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  • Processing XML comments in order using SAX & Cyberneko

    - by Joel
    I'm using cyberneko to clean and process html documents. I need to be able to process all the comments that occur in the original html documents. I've configured the cyberneko sax parser to process comments like so: parser.setProperty("http://xml.org/sax/properties/lexical-handler", consumer); ...using the same consumer as I am for DOM events. I get a callback for each of the comments: @Override public void comment(char[] arg0, int arg1, int arg2) throws SAXException { System.out.println("COMMENT::: "+new String(arg0, arg1, arg2)); } The problem I have is that all the comments are processed first, out of context of the DOM. i.e. I get a callback for all the comments before the document head, body etc.... What I'd like is for the comment callbacks to occur in the order they occur in the DOM. Edit: what I'm actually trying to do is parse the instructions for IE in the original html, such as: <!--[if lte IE 6]><body class="news ie"><![endif]--> At the moment they are all dropped, I need to include them in the cleaned HTML document.

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  • Adding and sorting a linked list in C

    - by user1202963
    In my assignment, I have to write a function that takes as arguments a pointer to a "LNode" structure and an integer argument. Then, I have to not only add that integer into the linked list, but also put place it so that the list is in proper ascending order. I've tried several various attempts at this, and this is my code as of posting. LNode* AddItem(LNode *headPtr, int newItem) { auto LNode *ptr = headPtr; ptr = malloc(sizeof(LNode)); if (headPtr == NULL) { ptr->value = newItem; ptr->next = headPtr; return ptr; } else { while (headPtr->value > newItem || ptr->next != NULL) { printf("While\n"); // This is simply to let me know how many times the loop runs headPtr = headPtr->next; } ptr->value = newItem; ptr->next = headPtr; return ptr; } } // end of "AddItem" When I run it, and try to insert say a 5 and then a 3, the 5 gets inserted, but then the while loop runs once and I get a segmentation fault. Also I cannot change the arguments as it's part of a skeletal code for this project. Thanks to anyone who can help. If it helps this is what the structure looks like typedef struct LNode { int value; struct LNode *next; } LNode;

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  • CustomButton Field not aligning in the center

    - by rupesh
    Hi all I have created a custom button and i am placing the bunch of Custombuttons in a verticalfieldManager , I have aligned the verticalField Manager in the center. when i am creating a default buttonField then verticalfield Manager is able to align the buttonfield in the center. but when i am assigning custombuttonfield in the verticalField Manager it's not aligning in the center. here is my custombuttoncode enter code herepublic CustomButtonField(String label,long style) { super(style); this.label = label; onPicture = Bitmap.getBitmapResource(onPicturePath); font = getFont(); this.setPadding(5,5, 5, 5); } public String getLabel() { return label; } public int getPreferredHeight() { return onPicture.getHeight(); } public int getPreferredWidth() { return onPicture.getWidth(); } protected void layout(int width , int height) { setExtent(Math.min(width, Display.getWidth()), Math.min(height,getPreferredHeight())); } protected void paint(Graphics graphics) { int texty =(getHeight()-getFont().getHeight())/2; if (isFocus()) { graphics.setColor(Color.BLACK); graphics.drawBitmap(0, 0, getWidth(), getHeight(),onPicture , 0, 0); graphics.setColor(Color.WHITE); graphics.setFont(font); graphics.drawText(label,0,texty,DrawStyle.ELLIPSIS,getWidth()); } else { graphics.drawBitmap(0, 0, getWidth(), getHeight(),onPicture , 0, 0); graphics.setColor(Color.WHITE); graphics.setFont(font); graphics.drawText(label,0,texty,DrawStyle.ELLIPSIS,getWidth()); } } public boolean isFocusable() { return true; } protected void onFocus(int direction) { super.onFocus(direction); invalidate(); } protected void onUnfocus() { super.onUnfocus(); invalidate(); } protected boolean navigationClick(int status, int time) { fieldChangeNotify(0); return true; } protected boolean keyChar(char character, int status, int time) { if (character == Keypad.KEY_ENTER) { fieldChangeNotify(0); return true; } return super.keyChar(character, status, time); } }

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  • Displaying cookies as key=value for all domains?

    - by OverTheRainbow
    Hello, This question pertains to the use of the cookie-capable WebClient derived class presented in the How can I get the WebClient to use Cookies? question. I'd like to use a ListBox to... 1) display each cookie individually as "key=value" (the For Each loop displays all of them as one string), and 2) be able to display all cookies, regardless of the domain from which they came ("www.google.com", here): Imports System.IO Imports System.Net Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim webClient As New CookieAwareWebClient Const URL = "http://www.google.com" Dim response As String response = webClient.DownloadString(URL) RichTextBox1.Text = response 'How to display cookies as key/value in ListBox? 'PREF=ID=5e770c1a9f279d5f:TM=1274032511:LM=1274032511:S=1RDPaKJKpoMT9T54 For Each mycc In webClient.cc.GetCookies(New Uri(URL)) ListBox1.Items.Add(mycc.ToString) Next End Sub End Class Public Class CookieAwareWebClient Inherits WebClient Public cc As New CookieContainer() Private lastPage As String Protected Overrides Function GetWebRequest(ByVal address As System.Uri) As System.Net.WebRequest Dim R = MyBase.GetWebRequest(address) If TypeOf R Is HttpWebRequest Then With DirectCast(R, HttpWebRequest) .CookieContainer = cc If Not lastPage Is Nothing Then .Referer = lastPage End If End With End If lastPage = address.ToString() Return R End Function End Class Thank you.

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  • Automatically converting an A* into a B*

    - by Xavier Nodet
    Hi, Suppose I'm given a class A. I would like to wrap pointers to it into a small class B, some kind of smart pointer, with the constraint that a B* is automatically converted to an A* so that I don't need to rewrite the code that already uses A*. I would therefore want to modify B so that the following compiles... struct A { void foo() {} }; template <class K> struct B { B(K* k) : _k(k) {} //operator K*() {return _k;} //K* operator->() {return _k;} private: K* _k; }; void doSomething(A*) {} void test() { A a; A* pointer_to_a (&a); B<A> b (pointer_to_a); //b->foo(); // I don't need those two... //doSomething(b); B<A>* pointer_to_b (&b); pointer_to_b->foo(); // 'foo' : is not a member of 'B<K>' doSomething(pointer_to_b); // 'doSomething' : cannot convert parameter 1 from 'B<K> *' to 'A *' } Note that B inheriting from A is not an option (instances of A are created in factories out of my control)... Is it possible? Thanks.

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  • Building argv and argc

    - by Wylie Coyote SG.
    I'm a student programmer using Qt to build a GUI application for work. The primary purpose of this application is to open some of our old style files, allows better editing and then save the file in a new format and file extension. Recently I have been asked to allow this conversion to take place from a terminal. While I do know what argv and argc are along with what they represent I am unsure how to accomplish what they want. For instance how to handle relative paths vs. absolute... maybe how to get absolute from relative; perhaps none of that is even needed. My programming experience has been primarily with guis so this is a little new to me. Users would like the following to be ran from the terminal application -o /fileLocation /fileDestination template(to determine new format) I began to use for loops and if statements to begin accomplishing this when I relized that I might be taking the worng approach to all of this. I WOULD ALSO BE REALLY INTERESTED IF QT HAS SOMETHING FOR THIS! Here is what I have began coming up with: int main(int argc, char *argv[]) { if(argc > 1) { for(int i = 0; i < argc; i++) { if(argv[i] == "-c") { QString fileName = QString::fromStdString(argv[i+1]); QString fileDestination = QString::fromStdString(argv[i+2]); QString templateName = QString::fromStdString(argv[i+3]); QFile fileToConvert(fileName); if(fileToConvert.open(QFile::ReadOnly)) { //do stuff Thanks for reading my post and a big thanks for any contributions you make to helping me overcome this issue.

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  • How to access the element of a list/vector that passed by reference in C++

    - by bsoundra
    Hi all, The problem is passing lists/vectors by reference int main(){ list<int> arr; //Adding few ints here to arr func1(&arr); return 0; } void func1(list<int> * arr){ // How Can I print the values here ? //I tried all the below , but it is erroring out. cout<<arr[0]; // error cout<<*arr[0];// error cout<<(*arr)[0];//error //How do I modify the value at the index 0 ? func2(arr);// Since it is already a pointer, I am passing just the address } void func2(list<int> *arr){ //How do I print and modify the values here ? I believe it should be the same as above but // just in case. } Is the vectors any different from the lists ? Thanks in advance. Any links where these things are explained elaborately will be of great help. Thanks again.

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  • C++, Ifstream opens local file but not file on HTTP Server

    - by fammi
    Hi, I am using ifstream to open a file and then read from it. My program works fine when i give location of the local file on my system. for eg /root/Desktop/abc.xxx works fine But once the location is on the http server the file fails to open. for eg http://192.168.0.10/abc.xxx fails to open. Is there any alternate for ifstream when using a URL address? thanks. part of the code where having problem: bool readTillEof = (endIndex == -1) ? true : false; // Open the file in binary mode and seek to the end to determine file size ifstream file ( fileName.c_str ( ), ios::in|ios::ate|ios::binary ); if ( file.is_open ( ) ) { long size = (long) file.tellg ( ); long numBytesRead; if ( readTillEof ) { numBytesRead = size - startIndex; } else { numBytesRead = endIndex - startIndex + 1; } // Allocate a new buffer ptr to read in the file data BufferSptr buf (new Buffer ( numBytesRead ) ); mpStreamingClientEngine->SetResponseBuffer ( nextRequest, buf ); // Seek to the start index of the byte range // and read the data file.seekg ( startIndex, ios::beg ); file.read ( (char *)buf->GetData(), numBytesRead ); // Pass on the data to the SCE // and signal completion of request mpStreamingClientEngine->HandleDataReceived( nextRequest, numBytesRead); mpStreamingClientEngine->MarkRequestCompleted( nextRequest ); // Close the file file.close ( ); } else { // Report error to the Streaming Client Engine // as unable to open file AHS_ERROR ( ConnectionManager, " Error while opening file \"%s\"\n", fileName.c_str ( ) ); mpStreamingClientEngine->HandleRequestFailed( nextRequest, CONNECTION_FAILED ); } }

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