#include<stdio.h>void main(){ float a,b,c; char x; printf("输入两个数和一个运算符号:\n"); scanf("%lf%lf%c",&a,&b,&c); if(x='+') c=a+b; if(x='-') c=a-b; if(x='*') c=a*b; if(x='/') c=a/b; printf("结果是:%lf\n",c); }