5-6.c

一些简单的c51程序

#include <REG52.H>                
#include <stdio.h>               
#include <ctype.h>

void main (void) {

	double sum,atof( char s[ ]);
	char sum1[10],sum2[10];

	SCON = 0x50; 
TMOD |= 0x20; 
TH1 = 0xf3; 
TR1 = 1;
TI = 1; 


	scanf("%s",sum1);
	scanf("%s",sum2);
	sum=atof(sum1)+atof(sum2);
	printf("%s+%s=%f\n", sum1,sum2,sum);
    while (1) {};
}

double atof( char s[ ])
{
	double val, power;
	int i, sign;
	for ( i = 0; isspace(s[i]); i++ ) /* 跳过空白*/;
		sign = (s[i] == '-' ) ? -1 : 1;
	if ( s[i] == '+' || s[i] == '-' )
		i++;
	for (val = 0.0; isdigit(s[i]); i++)
		val = 10.0 * val +(s[i] -'0' );
	if (s[i]  == '.')
		i++;
	for ( power = 1.0; isdigit(s[i]); i++) {
		val = 10.0 * val +(s[i] -'0' );
		power *= 10.0;
	}
	return sign * val / power;
}