API函数详解：Win2000图形绘制矩形与SineWave示例

//#define WINVER 0x0500  //WINVER>=0X500指Win2000以上。有些API或常数只有在Win2000以上才支持


#include <windows.h>                    
#include <math.h>  
#include <stdlib.h>  
//#define NUM   1000
//#define TWOPI  (2*3.14159)                
 
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;    //窗口过程函数申明

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)          //主函数定义 
{
     static TCHAR szAppName[] = TEXT (" SINEWAVE") ;
     HWND         hwnd ;                                   //定义窗口句柄
     MSG          msg ;                                    //定义消息对象
     WNDCLASS     wndclass ;/////////////////////////////////定义窗口类对象
     
     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;      // 窗口类中各变量的赋值
     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 (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;