#include <math.h>
main()
{float a1,a2,answer;char op;
scanf("%f",%f,%c",&a1,&a2,&op);
switch(op)
{ case "+":answer=a1+a2;break;
  case "-":answer=a1-a2;break;
  case "*":answer=a1*a2;break;
  case "/":answer=a1/a2;break;
  default:printf("OP Input ERROR！")；
}
  printf("Answer is %f\n",answer);
}

scanf("%f",%f,%c",&a1,&a2,&op);应该是
scanf("%f,%f,%c",&a1,&a2,&op);

case "/":answer=a1/a2;break;
是单引
case '/'

include <math.h>
int main(void){

        float a1,a2,answer;
        char op;
        scanf("%f,%f,%c",&a1,&a2,&op); //输入的时候要把逗号打上，比如：1,2，+

        switch(op) {
//对字符变量的检查，要用单引号，不能用双引号！！！切记！！！
        case '+':answer=a1+a2;break;
        case '-':answer=a1-a2;break;
        case '*':answer=a1*a2;break;
        case '.':answer=a1/a2;break;
        default:printf ("OP Input ERROR!");
        }
        printf("Answer is %f\n",answer);
        return 0;
}

[ 本帖最后由 ansic 于 2011-3-27 17:01 编辑 ]

先感谢了先··试一下～

还是有一个错误啊～～～

#include <stdio.h> /*用scanf要用这个头文件的吧*/
#include <math.h>
int main(void){

        float a1,a2,answer;
        char op;
        printf("choose + - * / :");
        scanf("%c",&op);

        printf("input a number A:");
        scanf("%f",&a1);

        printf("input a numbei B:");
        scanf("%f",&a2);

        switch(op) {
        case '+':answer=a1+a2;break;
        case '-':answer=a1-a2;break;
        case '*':answer=a1*a2;break;
        case '/':answer=a1/a2;break;
        default:printf ("OP Input ERROR!");
        }
        printf("Answer is %.2f\n",answer);
        return 0;
}

#include <stdio.h>

int main(void) {
    double a, b, c;
    char flag;
    int m, n, q, z;

     do {
     printf("\n----------\n");
     printf("简单计算机\n");
     printf("----------\n");
       do {
       printf("加法输入 '+', 减法输入 '-', 乘法输入 '*', 除法输入 '/'\n");
       printf("请输入:");

       scanf("%c", &flag);

       printf("你选择的是%c\n 是、按 1. \t不是、输入 0 \n请选择：",flag);
       scanf("%d", &z);
       } while (0 == z);

      if (flag == '+')
      m=1;

     else if (flag == '-')
      m=2;

     else if (flag == '*')
      m=3;

     else if (flag == '/')
      m=4;

     do {
      printf("运算a %c b\n",flag);
      printf("请输入a:");
      scanf("%lf",&a);

      printf("请输入b:");
      scanf("%lf",&b);
      printf("你想运算%.2lf %c %.2lf ?? \n是、请按1.\t不是、输入0\n", a, flag, b);

      scanf("%d",&q);
      } while (0 == q);

      switch (m) {
       case 1:
       c=a+b;
       break;

       case 2:
       c=a-b;
       break;

       case 3:
       c=a*b;
       break;

       case 4:
       c=a/b;
       break;
       }

     printf("%.2lf %c %.2lf=%.2lf", a, flag, b, c);
     printf("回到选择算法? \n是、输入1 \t 不是、输入0\n");
     scanf("%d", &n);
     }while (1 == n);
   return 0;
}
    

[ 本帖最后由 canxden 于 2011-3-27 17:17 编辑 ]

我英语很烂的= =

哦= =你以前写的好长哦