C++编程之美-代码清单1-4

// C++ code to make task manager generate sine graph
#include "Windows.h"
#include "stdlib.h"
#include "math.h"

const double SPLIT = 0.01;
const int COUNT = 200;
const double PI = 3.14159265;
const int INTERVAL = 300;

int _tmain(int argc, _TCHAR* argv[])
{
     DWORD busySpan[COUNT];		// array of busy times    
     DWORD idleSpan[COUNT];		// array of idle times
     int half = INTERVAL / 2;
     double radian = 0.0;
     for(int i = 0; i < COUNT; i++)
     {
          busySpan[i] = (DWORD)(half + (sin(PI * radian) * half));
          idleSpan[i] = INTERVAL - busySpan[i];
          radian += SPLIT;
     }

     DWORD startTime = 0;
     int j = 0;
     while(true)
     {
          j = j % COUNT;
          startTime = GetTickCount();
          while((GetTickCount() - startTime) <= busySpan[j])
              ;
          Sleep(idleSpan[j]);
          j++;
     }
     return 0;
}