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C language => Tips & tricks => Topic started by: Vortex on February 27, 2022, 02:02:00 PM

Title: Calling API functions in inline assembly code
Post by: Vortex on February 27, 2022, 02:02:00 PM

Hello,

Here is a quick example :

Code: [Select]

// Source code built with PellesC 11.00.2

#include <stdio.h>
#include <windows.h>
char t1[]="This is a test1.";
char t2[]="This is a test2.";

int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, WCHAR *pszCmdLine, int nCmdShow)
{
__asm{

push 0
push OFFSET t1
push OFFSET t1
        push 0
call DWORD PTR [MessageBox]
}

MessageBox(0,t2,t2,0);
return 0;
}

The API function MessageBox in the inline asm block should be enclosed between square brackets otherwise wrong call to API will lead to application crash.