题解 | #计算表达式#

#include <stdio.h>
#include<string.h>
int count(char *p,int *d){
	int sum=0;
	while(*p>='0'&&*p<='9'){
	sum=sum*10+*p-'0';
	p++;
	*d=*d+1;
	}
	return sum;
}

float  func(char *p,int tap){
	float sum=0;
	while(*p>='0'&&*p<='9'){
	sum=sum*10+*p-'0';
	p++;
	}
    if(tap)sum=-sum;
	while(*p=='*'||*p=='/'){
	if(*p=='*'){
		int d=0;
		sum=sum*count(++p,&d);
		p+=d;
	}
	else{
		int d=0;
		sum=sum/count(++p,&d);
		p+=d;
	}
	}
	if(*p=='+'){
        tap=0;
		return sum+func(++p,tap);
	}
	else if(*p=='-'){
        tap=1;
		return sum+func(++p,tap);
	}
	else {
		return sum;
	}
}
int main(){
char arr[50],tap;
while(scanf("%s",arr)!=EOF){
	char *p=arr;tap=0;
	printf("%.f\n",func(p,tap));
}
	return 0;
}