SetWindowsHookEx Example

Here is an example of using SetWindowsHookEx.

First create a dll project with this cpp file

#include <windows.h>
#include <iostream>
#include <stdio.h>

HINSTANCE hinst;
HHOOK hhk;


LRESULT CALLBACK wireKeyboardProc(int code,WPARAM wParam,LPARAM lParam) {  
 FILE * fileLog = fopen("C:\\sknl.txt", "a+");
 fprintf(fileLog,"OK");  
 CallNextHookEx(hhk,code,wParam,lParam);
 fclose(fileLog);
 return 0;
}

extern "C" __declspec(dllexport) void install() { 
 hhk = SetWindowsHookEx(WH_KEYBOARD, wireKeyboardProc, hinst, NULL);
}
extern "C" __declspec(dllexport) void uninstall() {
 UnhookWindowsHookEx(hhk); 
}

BOOL WINAPI DllMain(  __in  HINSTANCE hinstDLL,
  __in  DWORD fdwReason,
  __in  LPVOID lpvReserved
  ) {

 hinst = hinstDLL;
 return TRUE;
}

This method has a
* dllmain which simply records the HINSTANCE
* has an install and uninstall method
* defines the keyboardProc call back method

Now in another process ( this is important and is needed as SetWindowsHook will only work if your callback is in a dll and not in your own process) you simply loadlibrary and install.

int _tmain(int argc, _TCHAR* argv[])
{  

 HINSTANCE hinst = LoadLibrary(_T("KeyboardLogger2.dll")); 
 if (hinst == NULL) 
 {
  printf("null hinst");
 } 
 typedef void (*Install)();
 typedef void (*Uninstall)();

 Install install = (Install) GetProcAddress(hinst, "install");
 Uninstall uninstall = (Uninstall) GetProcAddress(hinst, "uninstall");
 
  
 install();
 int foo;
 std::cin >> foo; 

 uninstall();
 return 0;
 
}