1 #include 
     
       2 #include 
      
        3 int main() 4 {     5     double data1, data2; 6     char op; 7     while (3 == scanf("%lf%c%lf", &data1, &op, &data2) ) 8         {  9             double result;10             printf("%lf%c%lf=", data1,data2);11             switch (op)12             {13                 case '+':14                 result = data1 + data2;15                 break;16                 case '-':17                 result = data1 - data2;18                 break;    19                 case '*':20                 result = data1 * data2;21                 break;    22                 case '/':          23                 result = data1 / data2;24                 break;      25                 default:;26             }        27             printf("%lf\n", result);    28         }    29 30     return 0;31 }
      
     

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说明：上面的代码在计算特定运算时会出现舍入错误，原因待定，修改代码如下解决。

1 #include 
     
       2 int main() 3 {     4     float data1, data2; 5     char op; 6     while (3 == scanf("%f%c%f", &data1, &op, &data2) ) 7         {  8             float result; 9             printf("%f%c%f=", data1, op, data2);10 11             switch (op)12             {13                 case '+':14                 result = data1 + data2;15                 break;16                 case '-':17                 result = data1 - data2;18                 break;    19                 case '*':20                 result = data1 * data2;21                 break;    22                 case '/':          23                 result = data1 / data2;24                 break;      25                 default:;26             }        27             printf("%f\n", result);    28         }    29 30     return 0;31 }