c++

C/C++ definitions of functions

Yesterday, I have been watching discussion here, about compilers and linkers. It was about C library function definitions. I have never thought of that, so it inspired me to do some searching, but I cannot find exactly what I want. I wonder, what is the smallest syntax you need to add into your source code to enable just printf() functio...

What is the correct way to make sure user use shared_ptr and not regular ptr?

In my class the constructor is private and I added a static method "CreateMyClassPtr" that uses the constructor and returns a share_ptr of it. Is it the correct implementation? Do you think I even have to make sure that shared_ptr will be used? Should I maybe leave it to the user to decide? ...

Function return type style

I'm learning c++0x, at least the parts supported by the Visual C++ Express 2010 Beta. This is a question about style rather than how it works. Perhaps it's too early for style and good practice to have evolved yet for a standard that isn't even released yet... In c++0x you can define the return type of a method using -> type at the end ...

DST change handling in a daemon process (*NIX)

In a *NIX environment, if I have a 24x7 running application, how do I handle DST changes? I am looking for a solution for my app written in C/C++. ...

Is select() Ok to implement single socket read/write timeout ?

I have an application processing network communication with blocking calls. Each thread manages a single connection. I've added a timeout on the read and write operation by using select prior to read or write on the socket. Select is known to be inefficient when dealing with large number of sockets. But is it ok, in term of performance ...

Does operator new allocate on THREAD heap?

My problem seems to be this: heap data allocated by one thread (that later dies) seems to die as well. As so: Thread X: starts Thread Y: starts Thread X: ptr = new some bytes Thread X: dies Thread Y: tries to use ptr - and crashes! So far, I've only seen this problem on Darwin (Mac OS 10.5 and 10.6), but haven't tried more other plat...

How to differentiate two constructors with the same parameters?

Suppose we want two constructors for a class representing complex numbers: Complex (double re, double img) // construct from cartesian coordinates Complex (double A, double w) // construct from polar coordinates but the parameters (number and type) are the same: what is the more elegant way to identify what is intended? Adding a thir...

C++ threaded class design from non-threaded class

I'm working on a library doing audio encoding/decoding. The encoder shall be able to use multiple cores (i.e. multiple threads, using boost library), if available. What i have right now is a class that performs all encoding-relevant operations. The next step i want to take is to make that class threaded. So i'm wondering how to do this....

Safely remove window subclassing?

I am trying to subclass the currently focused window on a Windows system using a global CBT hook. This is related to what happens in this question, but the bug is different. What happens when this subclassing is in effect, is that Opera's (version 10.50) main window is prevented from displaying. Opera has a "splash screen" where you are...

I can't use std::vector of auto_ptr - should i use shared_ptr?

I don't really need to share the objects, but i do want to make sure no memory leakage occurs. Is it correct to use shared_ptr in this case? ...

Boost PropertyTree library with C++Builder?

Has anyone got tried this or got it working with Embarcadero C++Builder 2010 - If so, what did you need to do? ...

Why I am getting a Heap Corruption Error?

I am new to C++. I am getting HEAP CORRUPTION ERROR. Any help will be highly appreciated. Below is my code class CEntity { //some member variables CEntity(string section1,string section2); CEntity(); virtual ~CEntity(); //pure virtual function .. virtual CEntity* create()const = 0; }; I derive CLine from CEntity as...

getting window screenshot windows API

Hi, I am trying to make a program to work on top of an existing GUI to annotate it and provide extra calculations and statistical information. I want to do this using image recognition, as I have learned a fair amount about this in University using Matlab and similar things. I can get a handle to the window I want to perform image reco...

convert perl map with multiple key to c++

I want to convert a code from perl to c++, and my problem is multi key map in perl! example: perl: $address{name}{familyName} = $someAddress; and keys are not unique. I want similar data structure in c++ using map or ...!? also I want to search and obtain values with first key for example I want such %keys{name} in c++ . edited: I ...

Compiling C++ when two classes refer to one another

I am trying to write a simple wrapper around a connection pointer that will return it to the pool when the wrapper is destroyed, but it wont compile because the ConnectionPool and AutoConn need each other to be declared. I tried to use forward deceleration but it didn't work. How do I solve this? (using g++) class Connection {}; class...

Does std::vector change its address? How to avoid

Since vector elements are stored contiguously, I guess it may not have the same address after some push_back's , because the initial allocated space could not suffice. I'm working on a code where I need a reference to an element in a vector, like: int main(){ vector<int> v; v.push_back(1); int *ptr = &v[0]; for(int i=2;...

Default template arguments for function templates

Why are default template arguments only allowed on class templates? Why can't we define a default type in a member function template? For example: struct mycclass { template<class T=int> void mymember(T* vec) { // ... } }; Instead, C++ forces that default template arguments are only allowed on a class template. ...

How can I execute an Oracle procedure using UnixODBC?

I am trying to execute the procedure using execute <procedure_name>('A,'B'), but received an error that the SQL statement cannot be executed. What am I doing wrong? ...

Overloading assignment operator in C++

As I've understand, when overloading operator=, the return value should should be a non-const reference. A } It is non-const to allow non-const member functions to be called in cases like: ( a = b ).f(); But why should it return a reference? In what instance will it give a problem if the return value is not declared a reference, ...

Boost.MultiIndex: How to make an effective set intersection?

Hello, assume that we have a data1 and data2. How can I intersect them with std::set_intersect()? struct pID { int ID; unsigned int IDf;// postition in the file pID(int id,const unsigned int idf):ID(id),IDf(idf){} bool operator<(const pID& p)const { return ID<p.ID;} }; struct ID{}; struct IDf{}; typedef mul...