Question

am using CodeBlocks and am trying to make a hook dll so inside

DllMain

#include "main.h"
#include "Asm.h"
#include <stdio.h>
using namespace std;
    static HINSTANCE WINAPI Mysnprintf(char* str, int len, const char* format, ...);

    static void InitDll(){
        Originalsnprintf = (snprintfFn)GetProcAddress(GetModuleHandleA("msvcr90.dll"), "_snprintf");
        Asm code;
        code.JMP((int)Mysnprintf); // where JMP = Asm& JMP(int address){...}
    }

I have no clue what’s wrong since if I did the same with Microsoft Visual C++ it will work with no errors!!!

Answer 1

The linker tells you the function is undefined, and it’s right. You have not written a definition for your function. You’ve merely declared it.

Put some curly braces after the function and tell your compiler what you want that function to do:

static HINSTANCE WINAPI Mysnprintf(char* str, int len, const char* format, ...)
{
  ...
}