链接#include<stdio.h> int main() {double a,b; char ch; scanf("%lf%c%lf",&a,&ch,&b); if(ch=='+' || ch=='-' || ch=='/' || ch=='') {if(ch=='+') printf("%.4lf%c%.4lf=%.4lf",a,ch,b,a+b); if(ch=='-') printf("%.4lf%c%.4lf=%.4lf",a,ch,b,a-b); if(ch=='') printf("%.4lf%c%.4lf=%.4lf",a,ch,b,a*b); if(ch=='/')
{if(b==0.0) printf("Wrong!Division by zero!"); else printf("%.4lf%c%.4lf=%.4lf",a,ch,b,a/b);} } else {printf("Invalid operation!");} return 0;}