我想单击一个按钮弹出一个MessageBox对话框，但是我单击之后什么也没有，求解？

Question

下面是我的代码：

#include

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

struct
{
int iStyle;
TCHAR * szText;
}
button[] =
{
BS_PUSHBUTTON, TEXT("插入"),
BS_PUSHBUTTON, TEXT("删除"),
BS_PUSHBUTTON, TEXT("查找"),
BS_PUSHBUTTON, TEXT("退出"),
BS_PUSHBUTTON, TEXT("帮助")

};

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
int cxscreen = GetSystemMetrics(SM_CXSCREEN);
int cyscreen = GetSystemMetrics(SM_CYSCREEN);
static TCHAR szAppName[] = TEXT("studentadministratorsystem");
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)GetStockObject(GRAY_BRUSH);
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("学生信息管理系统"),
    WS_CLIPCHILDREN | WS_CLIPSIBLINGS | WS_POPUP,
    cxscreen/2-279/2,              
    cyscreen/2-392/2,              
    279,              
    392,              
    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)
{
static HWND hwndButton[5];
static int cxClient, cyClient;
static int cxChar, cyChar;

int i,inity=88;

switch (message)
{
case WM_SIZE:
    cxClient = LOWORD(lParam);
    cyClient = HIWORD(lParam);
    return 0;


case WM_CREATE: 

    for (i = 0; i < 5;i++)
    hwndButton[0] = CreateWindow(
        TEXT("button"),button[i].szText,WS_CHILD | WS_VISIBLE | button[0].iStyle,60,inity+39*(i),159,33,hwnd, (HMENU)i,
        ((LPCREATESTRUCT)lParam)->hInstance, NULL);
    return 0;

case WM_COMMAND:
    if (wParam ==0 )
        switch (HIWORD(lParam))
    {
        case BN_PUSHED: //按下
            MessageBox(hwnd, "按下按钮", "", 0);
            break;
    }
    break;
    return 0;

case WM_PAINT:

    return 0;

case WM_DESTROY:
    PostQuitMessage(0);
    return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);

}