C 控制台程序 小小计算器

#include <stdio.h>
/**//* 计算器小程序 */
int main()
{
    double number1 = 0.0;
    double number2 = 0.0;
    char operation = 0;
    
    start : printf("\n请入要计算的式子\n");
    scanf(" %lf %c %lf",&number1, &operation, &number2);
    
    /**//*  根据操作符号生成结果 */
    switch(operation)
    {
      case '+' :
        printf("=%lf\n", number1 + number2);
        break;
      case '-' :
        printf("=%lf\n", number1 - number2);
        break;
      case '*' :
        printf("=%lf\n", number1 * number2);
        break; 
      case '/' :
        if(number2 == 0)
        {
          printf("\n\n\a零不能作除数!\n");
        }
        else
        {
          printf("=%lf\n", number1 / number2);
        }
        break;
      case '%' :
        if((long)number2 == 0)
        {
           printf("\n\n\a零不能作除数!!\n");
        }
        else
        {
           printf("=%ld\n", (long)number1 % (long)number2);
        }
        break; 
      default:
        printf("\n\n\a输入参数不合法!\n");    
    }
    
    char isContinue = 0;
    printf("是否继续计算(Y/N): ");
    /**//* %c前面必须要有一个空格,不然读入的永远都是回车符 */
    scanf(" %c",&isContinue);
    
    /**//** 判断是否继续进行运算 */
    if(toupper(isContinue) == 'Y')
    {
      goto start;
    }
    return 0;
}