#include<stdio.h>
#include<stdlib.h>
#include <math.h>
int main()
{ float a,b,answer;
char op;
  printf("this is a simple calculator\n");
  printf("first of all, please input the operator,and then input the first number,and then input the other number\n");
  
  scanf("%f",&a);
  scanf("%c",&op);
  scanf("%f",&b);
  if(op=='+')
    {
      answer=a+b;
      printf("%f\n",answer);
    }
  else if(op=='-')
    {
      answer=a-b;
      printf("%f\n",answer);
    }
  else if(op='*')
    {
      answer=a*b;
      printf("%f\n",answer);
    }
  else if(op='/')
    {
      answer=a/b;
      printf("%f",answer);

    }
  return 0;
}
这个是我写的一个简单的计算器程序，不知道为什么运行错误，希望大家指点一下，谢谢。