c++

Providing *implicit* conversion operator for template specialization

I have a templated sparse_vector<T> class, and I am also using Boost UBLAS. How would I provide implicit conversions between sparse_vector<double> and boost::numeric::ublas::compressed_vector<double>? I would also like to provide similar conversions between std::vector<double> and boost::numeric::ublas::vector<double>. (I am using gcc...

Getting user input using cin.get() in C++ question

I'm not sure what I'm missing here. This is a snippet of code that I found on a site and I placed it in my program to see how it works and then I would modify it to my liking later. I am including iostream and this code snippet is in my main function. char buffer[80]; cout << "Enter the string: "; cin.get(buffer, 79); // get up ...

C++ putting a 2d array of floats into a char*

Hello, I'm trying to take a 2d vector of floats (input) and put them into a char* (output) in c++. void foo(const std::vector<std::vector<float> > &input, char* &output ) { char charBuf[sizeof(output)]; int counter = 0; for(unsigned int i=0; i<input.size(); i++) { for(unsigned int p=0; p<input.at(i).size(); p++) ...

multiple calls to realloc() seems to cause a heap corruption..

What's the problem with this code? It crashes every time. One time it's a failed assertion "_ASSERTE(_CrtIsValidHeapPointer(pUserData));", other times it is just a "heap corrpuption" error. Changing the buffer size affects this issue in some strange ways - sometimes it crashes on the "realloc", and other times on the "free". I have de...

How to use Unicode (UTF-8) in C++

Possible Duplicate: Unicode in C++ If I remembered correctly, the default character and string encoding in C++ are ASCII. Is there a simple way to enable Unicode support? ...

How do I indent/un-indent a QTextDocument?

What is the preferred way to indent/un-indent text in a list within a QTextDocument? Do I basically have to pass in the corresponding HTML tags myself? Edit: I'm looking for a way for the user to change the indentation level of a bulleted list with the Tab key. ...

How can I access the QUndoStack of a QTextDocument?

How can I access the QUndoStack of a QTextDocument? (For example, I want to be able to add custom QUndoCommand objects to the document's undo stack) ...

How to link Delphi with C++?

cpp.cpp extern "C" char* GetText() { return "Hello, world!"; } delphi.dpr {$APPTYPE CONSOLE} {$LINK 'cpp.obj'} function _GetText: PChar; cdecl; external; begin WriteLn(_GetText); end. I can't get this to work, no matter what I try. I tried various calling conventions, playing with underscores. even creating a .c wrapper for t...

Can a lambda expression be passed as function pointer?

I am trying to pass a lambda expression to a function that takes a function pointer, is this even possible? Here is some sample code, i'm using VS2010: #include <iostream> using namespace std; void func(int i){cout << "I'V BEEN CALLED: " << i <<endl;} void fptrfunc(void (*fptr)(int i), int j){fptr(j);} int main(){ fptrfunc(func,...

C++ pointers on example

I have a sample code : #include <iostream> #include <conio.h> using namespace std; int main () { int firstvalue = 5, secondvalue = 15; int * p1, * p2; p1 = &firstvalue; p2 = &secondvalue; cout << "1.p1: " << p1 << ", p2: " << p2 << endl; cout << "1.*p1: " << *p1 << ", *p2: " << *p2 << endl; *p1 = 10; cout << "2.p1: ...

Python - how to check if weak reference is still available

Hi all, I am passing some weakrefs from Python into C++ class, but C++ destructors are actively trying to access the ref when the real object is already dead, obviously it crashes... Is there any Python C/API approach to find out if Python reference is still alive or any other known workaround for this ? Thanks ...

tchar safe functions -- count parameter for UTF-8 constants

I'm porting a library from char to TCHAR. the count parameter of this fragment, according to MSDN, is the number of multibyte characters, not the number of bytes. so, did I get this right? My project properties in VC9 say 'use unicode character set' and I think that's correct, but I'm not how that impacts my count parameter. _tcsncmp(ac...

CM_Get_Device_ID gets correct values from win7 but not xp

When using CM_Get_Device_ID(...) I am getting the correct value from windows 7. When using windows xp I am getting an incorrect value. For Example, on xp I get "USB\VID_2132&PID_0001\5&36FF4167&0&7" and on 7 I get "USB\VID_2132&PID_0001\413031000576". The value after the \ on PID is our serial number and it is correct on 7 but xp keeps g...

How am i overriding this C++ inherited member function without the virtual keyword being used?

I have a small program to demonstrate simple inheritance. I am defining a Dog class which is derived from Mammal. Both classes share a simple member function called ToString(). How is Dog overriding the implementation in the Mammal class, when i'm not using the virtual keyword? (Do i even need to use the virtual keyword to override membe...

Need a fast test to see if a remote printer is available or not. Using CreateIC now, and when printer not up, 20 second delay.

My application does a CreateIC (and later, an OpenPrinter) for the user's default printer. When this is a remote printer, and that printer is powered down or otherwise not present on the network, it takes over 20 seconds for the CreateIC to return. I'm looking for some call I can make that will give me a quick answer if the server is...

Figure out texture coordinate from 4 others?

Lets say I have 4 verticies and their texture coordinates. How could I then figure out the texture coords of a 5th vertex? Thanks say I have: v1 = (0,0) tex coord(1,0) v2.... v3... v4... v5 = (15,15) tex coord = ?? yea linear interpolation I suppose, To figure out the coords I do: vec.x / polywidth; vec.y / polyheight; ...

C++: sizeof for array length

Let's say I have a macro called LengthOf(array): sizeof array / sizeof array[0] When I make a new array of size 23, shouldn't I get 23 back for LengthOf? WCHAR* str = new WCHAR[23]; str[22] = '\0'; size_t len = LengthOf(str); // len == 4 Why does len == 4? UPDATE: I made a typo, it's a WCHAR*, not a WCHAR**. ...

Creating simple calculator with bison & flex in C++ (not C)

Hey, I would like to create simple C++ calculator using bison and flex. Please note I'm new to the creating parsers. I already found few examples in bison/flex but they were all written in C. My goal is to create C++ code, where classes would contain nodes of values, operations, funcs - to create AST (evaluation would be done just afte...

Need help with events in COM in pure C++!

Hello, guys! Very important question: Please, look at my project (300Kb). I can`t use MFC/ATL, pure C++ only. I have COM library (niapi.dll), but no sources/headers available, dll only. There is class for connecting to server (NiApi::SrvrSession), class has login event handler (NiApi::SrvrSession::OnLogin). I used #import "NiApi.dll...

Is there any crossplatform C/C++ lib for files searching? (on hard drive)

Is there any crossplatform C\C++ lib for files searching? (on hard drive) What I need is simple - be able to find all images on users computer in all folders and subfolders with sise >= 200kb. How to do such thing? Can any one help me? Please. ...