CODEWITHSUNDEEP
cwindowswinapigcc
Snuff Movie
Snuff Movie

Reputation: 392

How do I link to libraries when compiling a win32 project with gcc?

I am trying to compile a basic hello word winform application with gcc on Win 7.

The code is this: 

/*

  WINHELLO.C

  "Hello, world!", Win32 style.

*/

#include <windows.h>

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


/*  WinMain(), our entry point  */

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
           LPSTR szCmdLine, int iCmdShow) {
    static char szAppName[] = "winhello";
    HWND        hwnd;
    MSG         msg;
    WNDCLASSEX  wndclass;


    /*  Fill in WNDCLASSEX struct members  */

    wndclass.cbSize         = sizeof(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.hIconSm        = LoadIcon(NULL, IDI_APPLICATION);
    wndclass.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wndclass.hbrBackground  = (HBRUSH) GetStockObject(WHITE_BRUSH);
    wndclass.lpszClassName  = szAppName;
    wndclass.lpszMenuName   = NULL;


    /*  Register a new window class with Windows  */

    RegisterClassEx(&wndclass);


    /*  Create a window based on our new class  */

    hwnd = CreateWindow(szAppName, "Hello, world!",
            WS_OVERLAPPEDWINDOW,
            CW_USEDEFAULT, CW_USEDEFAULT,
            CW_USEDEFAULT, CW_USEDEFAULT,
            NULL, NULL, hInstance, NULL);


    /*  Show and update our window  */

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


    /*  Retrieve and process messages until we get WM_QUIT  */

    while ( GetMessage(&msg, NULL, 0, 0) ) {
    TranslateMessage(&msg);    /*  for certain keyboard messages  */
    DispatchMessage(&msg);     /*  send message to WndProc        */
    } 


    /*  Exit with status specified in WM_QUIT message  */

    return msg.wParam;
}


/*  Window procedure  */

LRESULT CALLBACK WndProc(HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam) {
    PAINTSTRUCT ps;
    HDC         hdc;


    /*  Switch according to what type of message we have received  */

    switch ( iMsg ) {
    case WM_PAINT:

    /*  We receive WM_PAINT every time window is updated  */

    hdc = BeginPaint(hwnd, &ps);
    TextOut(hdc, 100, 100, "Hello, world!", 13);
    EndPaint(hwnd, &ps);
    return 0;

    case WM_DESTROY:

    /*  Window has been destroyed, so exit cleanly  */

    PostQuitMessage(0);
    return 0;
    }


    /*  Send any messages we don't handle to default window procedure  */

    return DefWindowProc(hwnd, iMsg, wParam, lParam);
}

The command I give to the compiler is gcc C:\Users\Bobby\Desktop\myfile.c

Well, it looks for libraries: 

C:\Users\Bobby\desktop>gcc C:\Users\Bobby\Desktop\myfile.c
C:\Users\Bobby\AppData\Local\Temp\ccT0bq97.o:myfile.c:(.text+0x88): undefined reference to `GetStockObject@4'
C:\Users\Bobby\AppData\Local\Temp\ccT0bq97.o:myfile.c:(.text+0x1db): undefined reference to `TextOutA@20'
collect2: ld returned 1 exit status
PS C:\Users\Scruffy\desktop> .\build.bat

C:\Users\Bobby\desktop>gcc C:\Users\Bobby\Desktop\myfile.c -I Gdi32.lib
C:\Users\Bobby\AppData\Local\Temp\ccylV5js.o:myfile.c:(.text+0x88): undefined reference to `GetStockObject@4'
C:\Users\Bobby\AppData\Local\Temp\ccylV5js.o:myfile.c:(.text+0x1db): undefined reference to `TextOutA@20'
collect2: ld returned 1 exit status
PS C:\Users\Bobby\desktop> C:\MinGW\

I did some googling and well I found out that this first GetStockObject@4 is in a file called Gdi32.lib . So i searched my harddrive and through MinGW and could not locate it. Where is the Lib to locate this function and what is the way to link to it? Also I think I must link to TextOutA@20

Upvotes: 3

Views: 8033

Answers (2)

aib
aib

Reputation: 46921

Instead of linking against GDI32 explicitly, you should use the -mwindows subsystem option in this case:

gcc -Wall -mwindows winhello.c -o winhello.exe

Note:

gcc et al. prefer .a files over .lib, so you should've been looking for libgdi32.a. You can still link against either by giving the filename as a parameter:

gcc src.c /path/to/example1.lib /path/to/libexample2.a

or using the -l option for .a files:

gcc src.c /path/to/example1.lib -L/path/to -lexample2

Upvotes: 10

Alex Cohn
Alex Cohn

Reputation: 57173

Windows DLL needs so-called import library for the linker to resolve references to its exported functions. Microsoft supplies import librarirs, including Gdi32.lib, with Windows SDK. This file should not be deployed to end users.

Upvotes: 0

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