fix an error of WNDCLASSEX in c program

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I am trying to create a windows application but when using WNDCLASSEX to define the window it shows an error. how i can rectified it. I am using Borland turbo C++ 4.5 compiler and only windows.h header file is added to it.

C++

int WINAPI WinMain(HINSTANCE hInstance,
						 HINSTANCE hPrevInstance,
						 LPSTR lpCmdLine,
						 int nCmdShow)
{
	 WNDCLASSEX wcex;

	 wcex.cbSize = sizeof(WNDCLASSEX);
	 wcex.style          = CS_HREDRAW | CS_VREDRAW;
	 wcex.lpfnWndProc    = WndProc;
	 wcex.cbClsExtra     = 0;
	 wcex.cbWndExtra     = 0;
	 wcex.hInstance      = hInstance;
	 wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
	 wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
	 wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;
	 wcex.lpszClassName  = szWindowClass;
	 wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
}

Posted 10-Feb-12 8:04am

mukesh bera

Updated 10-Feb-12 9:28am

CPallini

v2

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Comments

CPallini 10-Feb-12 15:06pm

"It shows an error"
Is not very informative. How could we help you? Please report the exact error message.

mukesh bera 10-Feb-12 15:17pm

The error is just "undefined symbol WNDCLASSEX is used"

CPallini 10-Feb-12 15:30pm

Did you put
#include <windows.h>
at the top of this source file?

mukesh bera 10-Feb-12 15:32pm

i put this header file in program and only this.

CPallini 10-Feb-12 15:35pm

What is your Operating System?

mukesh bera 10-Feb-12 15:39pm

i am using windows 7 ultimate 32 bit.

mukesh bera 10-Feb-12 15:40pm

does it may be a part of "stafx.h" header file

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TRK3 · Answer 1 · 2012-02-10T11:51:00

WINDCLASSEX is defined in WinUser.h, which is included by Windows.h:

C

#if(WINVER >= 0x0400)
typedef struct tagWNDCLASSEXA {
    UINT        cbSize;
    /* Win 3.x */
    UINT        style;
    WNDPROC     lpfnWndProc;
    int         cbClsExtra;
    int         cbWndExtra;
    HINSTANCE   hInstance;
    HICON       hIcon;
    HCURSOR     hCursor;
    HBRUSH      hbrBackground;
    LPCSTR      lpszMenuName;
    LPCSTR      lpszClassName;
    /* Win 4.0 */
    HICON       hIconSm;
} WNDCLASSEXA, *PWNDCLASSEXA, NEAR *NPWNDCLASSEXA, FAR *LPWNDCLASSEXA;
typedef struct tagWNDCLASSEXW {
    UINT        cbSize;
    /* Win 3.x */
    UINT        style;
    WNDPROC     lpfnWndProc;
    int         cbClsExtra;
    int         cbWndExtra;
    HINSTANCE   hInstance;
    HICON       hIcon;
    HCURSOR     hCursor;
    HBRUSH      hbrBackground;
    LPCWSTR     lpszMenuName;
    LPCWSTR     lpszClassName;
    /* Win 4.0 */
    HICON       hIconSm;
} WNDCLASSEXW, *PWNDCLASSEXW, NEAR *NPWNDCLASSEXW, FAR *LPWNDCLASSEXW;
#ifdef UNICODE
typedef WNDCLASSEXW WNDCLASSEX;
typedef PWNDCLASSEXW PWNDCLASSEX;
typedef NPWNDCLASSEXW NPWNDCLASSEX;
typedef LPWNDCLASSEXW LPWNDCLASSEX;
#else
typedef WNDCLASSEXA WNDCLASSEX;
typedef PWNDCLASSEXA PWNDCLASSEX;
typedef NPWNDCLASSEXA NPWNDCLASSEX;
typedef LPWNDCLASSEXA LPWNDCLASSEX;
#endif // UNICODE
#endif /* WINVER >= 0x0400 */

typedef struct tagWNDCLASSA {
    UINT        style;
    WNDPROC     lpfnWndProc;
    int         cbClsExtra;
    int         cbWndExtra;
    HINSTANCE   hInstance;
    HICON       hIcon;
    HCURSOR     hCursor;
    HBRUSH      hbrBackground;
    LPCSTR      lpszMenuName;
    LPCSTR      lpszClassName;
} WNDCLASSA, *PWNDCLASSA, NEAR *NPWNDCLASSA, FAR *LPWNDCLASSA;
typedef struct tagWNDCLASSW {
    UINT        style;
    WNDPROC     lpfnWndProc;
    int         cbClsExtra;
    int         cbWndExtra;
    HINSTANCE   hInstance;
    HICON       hIcon;
    HCURSOR     hCursor;
    HBRUSH      hbrBackground;
    LPCWSTR     lpszMenuName;
    LPCWSTR     lpszClassName;
} WNDCLASSW, *PWNDCLASSW, NEAR *NPWNDCLASSW, FAR *LPWNDCLASSW;
#ifdef UNICODE
typedef WNDCLASSW WNDCLASS;
typedef PWNDCLASSW PWNDCLASS;
typedef NPWNDCLASSW NPWNDCLASS;
typedef LPWNDCLASSW LPWNDCLASS;
#else
typedef WNDCLASSA WNDCLASS;
typedef PWNDCLASSA PWNDCLASS;
typedef NPWNDCLASSA NPWNDCLASS;
typedef LPWNDCLASSA LPWNDCLASS;
#endif // UNICODE

If you haven't defined WINVER at all, or haven't defined it to be greater than 0x0400, then it won't get defined.

The usual visual studio boilerplate stuff will define WINVER for you (normally in stdafx.h), but if you are using a Borland compiler you'll need to define WINVER somewhere (on the command line or in the code prior to including windows.h) in order to get WINDCLASSEX defined.