题解 | #简单计算器#

知识点：

分支控制：分支控制

if...else...

嵌套3个以上，建议用switch

#include <iostream>
using namespace std;

int main() {
    double n1;
    double n2;
    char ch;
    double res;

    scanf("%lf%c%lf", &n1, &ch, &n2);

    switch (ch) {
        case '+':
            printf("%.4f%c%.4f=%.4f", n1, ch, n2, n1 + n2);
            break;
        case '-':
            printf("%.4f%c%.4f=%.4f", n1, ch, n2, n1 - n2);
            break;
        case '*':
            printf("%.4f%c%.4f=%.4f", n1, ch, n2, n1 * n2);
            break;
        case '/':
            if (n2 == 0) {
                printf("Wrong!Division by zero!");
            } else {
                printf("%.4f%c%.4f=%.4f", n1, ch, n2, n1 / n2);
            }
            break;
        default:
            printf("Invalid operation!");
    }

    return 0;
}


// 解法一
/*
int main() {
    double n1;
    double n2;
    char ch;
    double res;

    scanf("%lf%c%lf", &n1, &ch, &n2);

    if (ch == '+') {
        printf("%.4f%c%.4f=%.4f", n1, ch, n2, n1 + n2);
    } else if (ch == '-') {
        printf("%.4f%c%.4f=%.4f", n1, ch, n2, n1 - n2);
    } else if (ch == '*') {
        printf("%.4f%c%.4f=%.4f", n1, ch, n2, n1 * n2);
    } else if (ch == '/') {
        if (n2 == 0) {
            printf("Wrong!Division by zero!");
        } else {
            printf("%.4f%c%.4f=%.4f", n1, ch, n2, n1 / n2);
        }
    } else {
        printf("Invalid operation!");
    }

    return 0;
}
*/