代码：
#include <windows.h>
#include <stdio.h>

LRESULT CALLBACK WinSunProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
);

int WINAPI WinMain(
  HINSTANCE hInstance,      // handle to current instance
  HINSTANCE hPrevInstance,  // handle to previous instance
  LPSTR lpCmdLine,          // command line
  int nCmdShow              // show state
)
{
    WNDCLASS wndcls;
    wndcls.cbClsExtra=0;
    wndcls.cbWndExtra=0;
    wndcls.hbrBackground=(HBRUSH)GetStockObject(BLACK_BRUSH);
    wndcls.hCursor=LoadCursor(NULL,IDC_CROSS);
    wndcls.hIcon=LoadIcon(NULL,IDI_ERROR);
    wndcls.hInstance=hInstance;
    wndcls.lpfnWndProc=WinSunProc;
    wndcls.lpszClassName="xin2003";
    wndcls.lpszMenuName=NULL;
    wndcls.style=CS_HREDRAW | CS_VREDRAW;
    RegisterClass(&wndcls);

    HWND hwnd;
    hwnd=CreateWindow("xin2003","科学技术培训中心",WS_OVERLAPPEDWINDOW,
        0,0,600,400,NULL,NULL,hInstance,NULL);

    ShowWindow(hwnd,SW_SHOWNORMAL);
    UpdateWindow(hwnd);

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

LRESULT CALLBACK WinSunProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
)
{
    switch(uMsg)
    {
    case WM_CHAR:
        char szChar[20];
        sprintf(szChar,"char is %d",wParam);
        MessageBox(hwnd,szChar,"weixin",0);
        break;
    case WM_LBUTTONDOWN:
        MessageBox(hwnd,"mouse clicked","weixin",0);
        HDC hdc;
        hdc=GetDC(hwnd);
        TextOut(hdc,0,50,"计算机编程语言培训",strlen("计算机编程语言培训"));
        ReleaseDC(hwnd,hdc);
        break;
    case WM_PAINT:
        HDC hDC;
        PAINTSTRUCT ps;
        hDC=BeginPaint(hwnd,&ps);
        TextOut(hDC,0,0,"培训",strlen("培训"));
        EndPaint(hwnd,&ps);
        break;
    case WM_CLOSE:
        if(IDYES==MessageBox(hwnd,"是否真的结束？","weixin",MB_YESNO))
        {
            DestroyWindow(hwnd);
        }
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hwnd,uMsg,wParam,lParam);
    }
    return 0;
}
报错：
Compiling...
WinMain.cpp
Linking...
LIBCD.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
Debug/WinMain.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

WinMain.exe - 2 error(s), 0 warning(s)
谢谢各位了，等待中

工程建错了

LZ建的是win32工程(入口函数是main),应该是 Window Application工程(入口函数是WinMain)