sample source MessageBox API Hook

i am trying Hook API,are you help me???,source or code

Click on "Search" on Google or Google Groups.
Hundreds of complete samples... (C, C++, asm Win32, etc)

It's not very clear what exactly you want to accomplish.
However, I hope this article from Codeguru can be a good starting point: Fancy Custom MessageBox.

Here is a sample of hooking MessageBox using Microsoft's Microsoft Detours

Code:

---

#pragma comment(lib, "detours.lib")
#pragma comment(lib, "detoured.lib")
#pragma comment(lib, "user32.lib")

#include <windows.h>
#include <stdio.h>
#include "detours.h"

#define ID_BUTTONMESSAGE  200

INT (WINAPI * trueMessageBox)(HWND hWnd, LPCSTR lpText, LPCSTR lpCaption, UINT uType) = MessageBox;

INT WINAPI hookedMessageBox(HWND hWnd, LPCSTR lpText, LPCSTR lpCaption, UINT uType)
{
    LPCSTR lpNewCaption = "You've been hijacked";
    int iReturn = trueMessageBox(hWnd, lpText, lpNewCaption, uType);
    return  iReturn;
}

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

VOID SetupDetour(void)
{
    DWORD dwError;
    DetourRestoreAfterWith();
    DetourTransactionBegin();
    DetourUpdateThread(GetCurrentThread());
    DetourAttach(&(PVOID&)trueMessageBox, hookedMessageBox);
    dwError = DetourTransactionCommit();
    if (dwError == NO_ERROR)
        MessageBox(NULL, "MessageBox hook installed successfully", "HOOK", MB_OK);
    else
        MessageBox(NULL, "MessageBox hook installation failed", "Error", MB_OK);
}

INT WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
    static TCHAR szAppName[] = TEXT ("MessageBox Hook") ;
    HWND        hwnd ;
    MSG          msg ;
    WNDCLASS    wndclass ;

    wndclass.style        = CS_HREDRAW | CS_VREDRAW ;
    wndclass.lpfnWndProc  = WndProc ;
    wndclass.cbClsExtra    = 0 ;
    wndclass.cbWndExtra    = 0 ;
    wndclass.hInstance    = hInstance ;
    wndclass.hIcon        = LoadIcon (NULL, IDI_APPLICATION) ;
    wndclass.hCursor      = LoadCursor (NULL, IDC_ARROW) ;
    wndclass.hbrBackground = (HBRUSH) GetSysColorBrush(COLOR_3DFACE) ;
    wndclass.lpszMenuName  = NULL ;
    wndclass.lpszClassName = szAppName ;

    if (!RegisterClass (&wndclass))
    {
        MessageBox (NULL, TEXT ("This program requires Windows NT!"),
            szAppName, MB_ICONERROR) ;
        return 0 ;
    }
    hwnd = CreateWindow (szAppName,                 
        TEXT ("MessageBox Hook"),
        WS_OVERLAPPEDWINDOW,       
        CW_USEDEFAULT,             
        CW_USEDEFAULT,             
        700,             
        300,           
        NULL,                     
        NULL,                     
        hInstance,                 
        NULL) ;                   

    ShowWindow (hwnd, iCmdShow) ;
    UpdateWindow (hwnd) ;

    while (GetMessage (&msg, NULL, 0, 0))
    {
        TranslateMessage (&msg) ;
        DispatchMessage (&msg) ;
    }
    return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
        case WM_CREATE:
            CreateWindow( "button", "Display MessageBox",   
                WS_VISIBLE | WS_CHILD ,
                200, 50, 180, 25,       
                hwnd, (HMENU) ID_BUTTONMESSAGE, NULL, NULL);
            SetupDetour();
            return 0 ;
        case WM_COMMAND:
            switch(LOWORD(wParam))
            {
                case ID_BUTTONMESSAGE:
                    MessageBox(hwnd, "This is a test of the hook, note caption", "Test", MB_OK);
                  break;
            }
            break;;
        case WM_DESTROY:
            PostQuitMessage (0) ;
            return 0 ;
    }
    return DefWindowProc (hwnd, message, wParam, lParam) ;
}

---

Try this one:
http://www.codeguru.com/forum/showthread.php?t=469549

@BobS0327 Hi I managed to get the above code working, though I would like to know if there is a way to make this work across different processes e.g. notepad.exe?