VC++编程中遇到的问题

Question

在编API函数时，怎么老是说WndProc这个函数undeclared identifier，请高手帮忙解答一下！！！谢谢！！！

Answer 1

程序是这个样子的，我试过了，还是错误的！！！怎么办？？？？？？
#include <windows.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>LRESULT CALLBACK Wndproc(HWND,UINT,WPARAM,LPARAM);  //窗口函数的声明int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInst,LPSTR lpszCmdLine,int 
   nCmdShow)
{
HWND hwnd;
MSG Msg;
WNDCLASS wndclass;
char lpszClassName[]="WinFill";
char lpszTitle[]="绘制射线程序";
wndclass.style=0;
wndclass.lpfnWndProc=(WNDPROC)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)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName=NULL;
wndclass.lpszClassName=lpszClassName;
if (!RegisterClass(&wndclass))
{
MessageBeep(0);
return FALSE;
}
hwnd=CreateWindow
(
lpszClassName,
lpszTitle,
WS_OVERLAPPEDWINDOW,
    CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL
);
ShowWindow(hwnd,nCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&Msg,NULL,0,0))
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}
LRESULT CALLBACK Wndproc(HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam)
{
HDC hdc;
PAINTSTRUCT ps;
    static POINT p1;
static POINT p2[20];
static int i;
switch(Msg)
{
case WM_RBUTTONDOWN:
p1.x=LOWORD(lParam);
p1.y=HIWORD(lParam);
InvalidateRect(hwnd,NULL,1);
break;
case WM_RBUTTONUP:
        InvalidateRect(hwnd,NULL,1);
break;
case WM_MOUSEMOVE:
if((wParam & MK_LBUTTON) && i < 20)
{
for(i=0;i<20;i++)
{
p2[i].x=LOWORD(lParam);
        p2[i].y=HIWORD(lParam);
hdc=GetDC(hwnd);
                SetPixel (hdc, LOWORD (lParam), HIWORD (lParam), 0L);
ReleaseDC(hwnd,hdc);
}
}
break;
case WM_PAINT:
hdc=BeginPaint(hwnd,&ps);
for(i=0;i<20;i++)
{
MoveToEx(hdc,p1.x,p1.y,NULL);
    LineTo(hdc,p2[i].x,p2[i].y);
}
EndPaint(hwnd,&ps);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd,Msg,wParam,lParam);
}
return 0;
}

Answer 2

wndclass.lpfnWndProc=(WNDPROC)WndProc;改成wndclass.lpfnWndProc=WndProc；
你再试一下！

Answer 3

LRESULT CALLBACK Wndproc(HWND,UINT,WPARAM,LPARAM);  
Wndproc-->WndProc

Answer 4

注意大小写：
LRESULT CALLBACK Wndproc(HWND,UINT,WPARAM,LPARAM);  //窗口函数的声明//p小写
wndclass.lpfnWndProc=(WNDPROC)WndProc; //P大写
LRESULT CALLBACK Wndproc(HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam) //p小写C语言是大小写敏感的，名称要统一大小写