API 1

#include <Windows.h>

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow){

    HWND hMainWnd;
    char *szClassName="MYClass";
    MSG msg;
    WNDCLASSEX wc;

    wc.cbSize=sizeof(wc);
    wc.style=CS_HREDRAW|CS_VREDRAW;
    wc.lpfnWndProc=WndProc;
    wc.cbClsExtra=0;
    wc.cbWndExtra=0;
    wc.hInstance=hInstance;
    wc.hIcon=LoadIcon(NULL,IDI_APPLICATION);
    wc.hCursor=LoadCursor(NULL,IDC_ARROW);
    wc.hbrBackground=(HBRUSH)GetStockObject(GRAY_BRUSH);
    wc.lpszMenuName=NULL;
    wc.lpszClassName=szClassName;
    wc.hIconSm=LoadIcon(NULL,IDI_APPLICATION);

    if(!RegisterClassEx(&wc))return 0;

    hMainWnd = CreateWindow(szClassName, "Application 1",
    WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0, CW_USEDEFAULT, 0,
    (HWND)NULL, (HMENU)NULL, (HINSTANCE)hInstance, NULL );

    if(!hMainWnd)return 0;

    ShowWindow(hMainWnd,nCmdShow);

    while(GetMessage(&msg,NULL,0,0)){
    TranslateMessage(&msg);
    DispatchMessage(&msg);
    }
    return 0;
}
LRESULT CALLBACK WndProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam){
HDC hDC;
PAINTSTRUCT ps;
RECT rect;

switch(uMsg){
case WM_PAINT:
    hDC=BeginPaint(hWnd,&ps);

    GetClientRect(hWnd,&rect);
    DrawText(hDC,"hello",-1,&rect,DT_SINGLELINE|DT_CENTER|DT_VCENTER);
    EndPaint(hWnd,&ps);
    break;
case WM_CLOSE:
    DestroyWindow(hWnd);
    break;
case WM_DESTROY:
    PostQuitMessage(0);
    break;
default:
    return DefWindowProc(hWnd,uMsg,wParam,lParam);
}
return 0;
}