siren.c

来自「C_C++程序员实用大全（精华版）源代码 代码详实 一步一步深入 适合各阶段」· C语言 代码 · 共 24 行

#include <dos.h>
#include <conio.h>

void main(void)
 {
   unsigned frequency;

   do 
   {
     for (frequency = 500; frequency <= 1000; frequency += 50)
      { 
       sound(frequency);
       delay(50);
      }
     for (frequency = 1000; frequency >= 500; frequency -= 50)
      { 
       sound(frequency);
       delay(50);
      }
   } 
	 while (! kbhit());
   nosound();
 }