题解 | #实现简单计算器功能#

#include <iostream>
#include <string>
#include <sstream>

using namespace std;

double performOperation(const string &opt, int num1, int num2) {
    if (opt == "add") return num1 + num2;
    else if (opt == "sub") return num1 - num2;
    else if (opt == "mul") return num1 * num2;
    else if (opt == "div") {
        if (num2 == 0) {
            cout << "Error" << endl;
            exit(EXIT_FAILURE);
        }
        return  num1 / num2;
    } else {
        cout << "Error: Invalid operation.\n";
        exit(EXIT_FAILURE);
    }

}

int main() {

    char str[100] = {0};
    cin.getline(str, sizeof(str));

    // write your code here......
    string input = str;
    string opt;
    int num1, num2;

    istringstream iss(input);
    iss >> opt >> num1 >> num2;

    for (char &c: opt) {
        c = tolower(c);
    }
    double res = performOperation(opt, num1, num2);
    cout << res << endl;

    return 0;
}

虽然题目未说明是否允许使用字符串分割的类，但为了后续的学习和规范地编码，了解一下也未尝不可