Question

我是C ++语言的新手，正在上课。我有一个需要三个函数的编程任务。

功能一是显示菜单并获取用户数据。
功能二是根据用户数据的选择来计算用户数据。
功能三是输出数据。

我一直在尝试按照教程，但我没有抓住它。
这是我的代码：

#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <fstream>
#include <string>
#include <cmath>
using namespace std;

double userNumber = 0;
double calcNum_one = 0;
double calcNum_two = 0;

void menu();
double calculator(double, double);
void solution();

int main() {
    do {
        menu();
        calculator(answer);
        solution();
    }
    while (userNumber != 7);

    return 0;
}

void menu () {
    cout << "Welcome to the CIS 151 calculator." << endl;
    cout << "To make a selection, enter the number and press enter." << endl;
    cout << "   1. Add two numbers." << endl;
    cout << "   2. Subtract one number from another." << endl;
    cout << "   3. Multiply two numbers." << endl;
    cout << "   4. Divide two numbers." << endl;
    cout << "   5. Modulus of two numbers." << endl;
    cout << "   6. Raise a number to a power." << endl;
    cout << "   7. Quit the program." << endl;
    cout << endl;
    cout << "Number: ";
    cin >> userNumber;
}

void calculator(double calcNum_one, double calcNum_two) {
    if(userNumber == 1) {
        system("CLS");
        cout << "You have chosen to: add two numbers." << endl;
        cout << "Please type in your numbers." << endl;
        cout << endl;
        cout << "First Number: ";
        cin >> calcNum_one;
        cout << "Second Number: ";
        cin >> calcNum_two;

        double answer = calcNum_one + calcNum_two;
        return answer;
    }
}

void solution() {
    if(userNumber == 1) {
        system("CLS");
        cout << "The sum of " << calcNum_one << " and " << calcNum_two << " is " << answer << "." << endl;
        cout << endl;
        system("PAUSE");
    }
}

注意：我只是将if语句放在一个可能的位置，以便于阅读。

有人可以清理我的代码以显示我如何正确使用计算器功能吗？我在CodeBlocks中获得error: 'answer' was not declared in this scope。

谢谢大家！

Answer 1

answer未声明，因此无法使用。

您决定使用全球视觉效果，因此请始终如一地使用它们。

#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <fstream>
#include <string>
#include <cmath>
using namespace std;

double userNumber = 0;
double calcNum_one = 0;
double calcNum_two = 0;
double answer = 0;

void menu();
void calculator();
void solution();

int main() {
    do {
        menu();
        calculator();
        solution();
    }
    while (userNumber != 7);

    return 0;
}

void menu () {
    cout << "Welcome to the CIS 151 calculator." << endl;
    cout << "To make a selection, enter the number and press enter." << endl;
    cout << "   1. Add two numbers." << endl;
    cout << "   2. Subtract one number from another." << endl;
    cout << "   3. Multiply two numbers." << endl;
    cout << "   4. Divide two numbers." << endl;
    cout << "   5. Modulus of two numbers." << endl;
    cout << "   6. Raise a number to a power." << endl;
    cout << "   7. Quit the program." << endl;
    cout << endl;
    cout << "Number: ";
    cin >> userNumber;
}

void calculator() {
    if(userNumber == 1) {
        system("CLS");
        cout << "You have chosen to: add two numbers." << endl;
        cout << "Please type in your numbers." << endl;
        cout << endl;
        cout << "First Number: ";
        cin >> calcNum_one;
        cout << "Second Number: ";
        cin >> calcNum_two;

        answer = calcNum_one + calcNum_two;
    }
}

void solution() {
    if(userNumber == 1) {
        system("CLS");
        cout << "The sum of " << calcNum_one << " and " << calcNum_two << " is " << answer << "." << endl;
        cout << endl;
        system("PAUSE");
    }
}

当然你不应该使用全局变量。某些人也憎恨using namespace std;甚至using。

#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <fstream>
#include <string>
#include <cmath>

double menu();
double calculator(double&, double&, double);
void solution(double, double, double, double);

int main() {
    double userNumber;
    double calcNum_one;
    double calcNum_two;
    double answer;
    do {
        userNumber = menu();
        answer = calculator(calcNum_one, calcNum_two, userNumber);
        solution(calcNum_one, calcNum_two, answer, userNumber);
    }
    while (userNumber != 7);

    return 0;
}

double menu () {
    double userNumber;
    std::cout << "Welcome to the CIS 151 calculator." << std::endl;
    std::cout << "To make a selection, enter the number and press enter." << std::endl;
    std::cout << "   1. Add two numbers." << std::endl;
    std::cout << "   2. Subtract one number from another." << std::endl;
    std::cout << "   3. Multiply two numbers." << std::endl;
    std::cout << "   4. Divide two numbers." << std::endl;
    std::cout << "   5. Modulus of two numbers." << std::endl;
    std::cout << "   6. Raise a number to a power." << std::endl;
    std::cout << "   7. Quit the program." << std::endl;
    std::cout << std::endl;
    std::cout << "Number: ";
    std::cin >> userNumber;
    return userNumber;
}

double calculator(double& calcNum_one, double& calcNum_two, double userNumber) {
    double answer = 0;
    if(userNumber == 1) {
        system("CLS");
        std::cout << "You have chosen to: add two numbers." << std::endl;
        std::cout << "Please type in your numbers." << std::endl;
        std::cout << std::endl;
        std::cout << "First Number: ";
        std::cin >> calcNum_one;
        std::cout << "Second Number: ";
        std::cin >> calcNum_two;

        answer = calcNum_one + calcNum_two;
    }
    return answer;
}

void solution(double calcNum_one, double calcNum_two, double answer, double userNumber) {
    if(userNumber == 1) {
        system("CLS");
        std::cout << "The sum of " << calcNum_one << " and " << calcNum_two << " is " << answer << "." << std::endl;
        std::cout << std::endl;
        system("PAUSE");
    }
}

正确使用C ++中的函数？

1 个答案: