Patrick’s development blog

Preparing the Win32 API

Posted in Uncategorized by Patrick on March 25, 2008

I’ve started to learn a little Windows coding using its API today. I’m preparing it for my chat application i’m going to make in C++. Here’s how a typical hello world program looks like when coding in win32. It displays a message box on the screen which says “Hello world”.

Hello world in Win32

#include <windows.h>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) {
MessageBox(NULL, TEXT(“Hello world!”), TEXT(“Message”), 0);
return 0;

WinMain is the same as the main() function in C and C++ (the entry point of the application).

The hInstance parameter is a handler to the current window. It seems that the second parameter hPrevInstance isn’t used anymore. It was used to keep track of other instances of the same application. Last time it was used was in 16-bit Windows. The parameter is always NULL.

The third parameter szCmdLine takes care of the commands the application is started with.

The last parameter iCmdShow indicates how the program should be displayed, for example if it’s going to be maximized, minimized or hidden.