¿Qué es WinMain en C?

What is WinMain in C?

WinMain() is the C entry point function of any windows application. Like normal DOS/console based application which has main() function as C entry point, in windows we have WinMain() instead. WinMain() is a function which is called by system during creation of a process.

In computer programming, an entry point is a point in a program where the execution of a program begins, and where the program has access to command line arguments. To start a program’s execution, the loader or operating system passes control to its entry point.

The main function is special because it is entry point for program execution. It plays the role of door in a house. Similarly, main function is important and compulsory as execution starts from here.

1. You have to either custom link the two object files created from compiling the two .cpps or put the files in a project. –
2. I do not know codeblocks but you need to enable subsystem CONSOLE – drescherjm Jan 14 ’14 at 2:46.
3. @drescherjm, No, that has nothing to do with the problem.

Main vs WinMain. WinMain() is the C entry point function of any windows application. Like normal DOS/console based application which has main() function as C entry point, in windows we have WinMain() instead. WinMain() is a function which is called by system during creation of a process. First argument is the instance handle of the current process.

WinMain takes 4 parameters that are passed to the program by Win O/S at start up: int WINAPI WinMain( HINSTANCE hInstance, // HANDLE TO AN INSTANCE. This is the “handle” to YOUR PROGRAM ITSELF.

All 32-bit Windows operating system applications use the calling convention WINAPI. This calling convention MUST be used to distinguish the function as the entry point. Now for the parameters. As you can see, WinMain uses four parameters when the program starts. Let’s have a look at them, shall we?

The CRT does some additional work inside main. For example, any static initializers are called before wWinMain. Although you can tell the linker to use a different entry-point function, use the default if you link to the CRT. Otherwise, the CRT initialization code will be skipped, with unpredictable results.

Parameters

• hInst – Handle to the current running instance of the application.
• hPrevInst – Handle to the previous instance of the process.
• strCmdLine – Pointer to a null-terminated ASCII string holding the input command line from the , excluding the program name.
• nCmdShow – Specifies how the window is to be shown.

The __clrcall modifier is Microsoft-specific. Use __clrcall to improve performance when calling from a managed function to a virtual managed function or from managed function to managed function through pointer. Entry points are separate, compiler-generated functions.

hInstance and hPrevInstance: – are parameters of the WinMain function, hInstance is the handle to the current instance of the application, and the hPrevInstance is a handle to the previous instance of the application, hPrevInstance is always NULL.

__cdecl is the default calling convention for C and C++ programs. Because the stack is cleaned up by the caller, it can do vararg functions. Place the __cdecl modifier before a variable or a function name.

This function gives the driver the means to return information to an application or DLL while continuing to process a request. If a driver supports callback functions, the application or DLL that opens the instance must supply a value this is either the address of a callback function, a window handle, or a task handle.

This will produce an object file only, which needs to be linked into either a static or shared lib or an application (in which case you’ll need an oject file with main defined). _WinMain is Microsoft’s name for main when linking. Also: you’re not running the code yet, you are compiling (and linking) it. C++ is not an interpreted language.

WinMain returns success as zero and error as non zero. The WinMain function is called by the system as the initial entry point for a Win32-based application. hInstance – Handle to the current instance of the application. hPrevInstance – Handle to the previous instance of the application. For a Win32-based application, this parameter is always NULL.