C語言學習第三章：計算器

C語言寫出來的簡單計算器
do…while無限回圈中套入switch

#include<stdio.h>

int main(void)
{
    char operator;
    int esc;
    double a, b, c;

    do
    {
        printf("請輸入運算子。\n");
        printf("提醒：按q鍵退出計算器\n");
        scanf_s(" %c", &operator, 1);
        if (operator == 'q') {
            return (1);
        }
        if (operator != '+' && operator != '-' && operator != '*' && operator!='/') {
            printf("運算子錯誤，請重新輸入ー\n");
            continue;
        }

        printf("請輸入數位。\n");
        scanf_s("%lf%lf", &a, &b);

        esc = 1;

        switch (operator)
        {
        case '+':            
            c = a+b;
            break;
        case '-':
            c = a-b;
            break;
        case '*':
            c = a*b;
            break;
        case '/':
            if (b == 0) {
                printf("錯誤：除數不能爲0\n");
                esc = 0;
                break;
            }
            c = a/b;
            break;
        }
        if (esc != 0) {
            printf("%lf%c%lf = %g\n", a, operator, b, c);
        }
    } while(1);

return 0;
}