题解 | #加减乘除#

#include <stdio.h>

int main(){
    int x, y;
    char sign;
    while(scanf("%d %c",&x, &sign) != EOF){
        int result = 1;     //阶乘时使用
        if(sign == '!'){
            for (int i = 1; i <= x; ++i) {
                result *= i;
            }
            printf("%d\n", result);
        }
        else{
            scanf("%d", &y);
            switch(sign){
                case '+':
                    printf("%d\n", x+y);break;
                case '-':
                    printf("%d\n", x-y);break;
                case '*':
                    printf("%d\n", x*y);break;
                case '/':
                    if (y == 0){
                        printf("error\n");break;
                    }
                    else{
                        printf("%d", x/y);break;
                    }
                case '%':
                    if (y == 0){
                        printf("error\n");break;
                    }
                    else{
                        printf("%d", x%y);break;
                    }
            }
        }
    }
    return 0;
}