7-1.c

一些简单的c51程序

#include <reg51.h>
#include <stdio.h>
#define  PI  3.14159              
main()
{
int s,r=5;
s=PI*r*r;

SCON = 0x50; 
TMOD |= 0x20; 
TH1 = 0xf3; 
TR1 = 1;
TI = 1; 
printf ("%d\n",s);
}