为什么我的程序没有处理所有功能？

Question

大家好！首先我想让大家知道我是 C++ 的初学者，所以我的代码会有很多错误。 我试图制作一个程序来刷新我的 C++ 概念。我面临的问题是程序正在询问我的电子邮件 ID，但是一旦我输入它，程序就结束了。请让我知道我做错的一切以及如何纠正它。非常感谢！

我决定使用以下算法创建一个简单的登录程序：

1. 它要求用户提供他们的电子邮件 ID。
2. 检查电子邮件是否已注册（在文本文件中）
3. 如果电子邮件已注册，则会提示用户输入密码。
4. 如果密码正确，则打印成功消息；如果没有，用户会再尝试 2 次。
5. 如果电子邮件未注册，程序会提示用户输入新密码并告诉他们密码强度。理想的密码应该是一个大写字母、一个小写字母和一个数字，密码长度大于6个字符。

数据.h：

#include <iostream>
#include <string>

using namespace std;

#ifndef DATA_H
#define DATA_H


struct newAccount{


    string email, password; //declaring email and password of the user
};

    string readEmail(string email); //reads in the email id provided
    void checkEmail(); //checks if the entered email address exists in the system
    int addEmail(); //checks if the entered email address exists in the system

    void checkPassword(); //checks if the password matches an already registered email id
    void makeNewPassword(string& password); //this function helps the user create a secure password


#endif

数据.cpp：

#include <iostream>
#include <string>
#include <fstream>
#include "data.h"

using namespace std;

newAccount tempAccount;

string readEmail(string email) //reads in the email id provided
{
    cout << "Enter an email address: ";
    getline(cin, tempAccount.email);
    email = tempAccount.email;
    return tempAccount.email;
}

void checkEmail()
{
    ifstream file("database.txt");
    string str;
    while (getline(file, str))
    {
        if (str == tempAccount.email)
        {
            cout << "This email is already registered. Please enter your password: ";
            getline(cin, tempAccount.password);
            checkPassword();
        }

        else
        {
            cout << "This email is not registered. Please create a new password: ";
            makeNewPassword(tempAccount.password);
        }
    }
}

int addEmail() //checks if the entered email address exists in the system
{
    ofstream myFile("database.txt");
    if (myFile.is_open())
    {
        myFile << tempAccount.email << endl;
        myFile.close();
    }
    else
        cout << "Unable to open file";
    return 0;
}

void checkPassword() //checks if the password matches an already registered email id
{
    ifstream file("database.txt");
    string str;
    while (getline(file, str))
    {
        if (checkEmail)
        {
            if (str == tempAccount.password)
            {
                cout << "Login successful! ";
                getline(cin, tempAccount.password);
            }

            else
                for (int i = 4; i > 1; i--)
                {
                    cout << "Incorrect password! You have " << i - 1 << " tries remaining.\n";
                    if (str == tempAccount.password)
                        break;
                }
        }
    }
}

void makeNewPassword(string &password) //this function helps the user create a secure password
{
    int n = password.length();
    bool hasLower = false, hasUpper = false, hasDigit = false;

    for (int i = 0; i < n; i++)
    {
        if (islower(password[i]))
            hasLower = true;
        if (isupper(password[i]))
            hasUpper = true;
        if (isdigit(password[i]))
            hasDigit = true;
    }

    // Displaying the strength of password

    cout << "Strength of password you have entered is ";

    if (hasUpper && hasDigit && hasLower && (n >= 6)) // considering a strong must be of length 6 or more
        cout << "strong" << endl;
    else if ((hasLower || hasUpper) && hasDigit && (n >= 6))
        //when at least a lower case or uppercase is used along with digit
        cout << "moderate" << endl;
    else
        cout << "weak" << endl;
}

main.cpp

#include <iostream>
#include <fstream>
#include "data.h"

using namespace std;

int main(){
    string e, p;
    readEmail(e);
    checkEmail();
return 0;
}

我使用几个学期前学习的几门基本 C++ 课程的知识以及使用在线教程创建了这个程序。这不是家庭作业或任何形式的作业。

Answer 1

在您的 readEmail() 函数中，字符串 email 是一个局部变量。您通过值而不是通过引用将变量传递给函数。 此外，如果您通过引用传递它，则无需返回任何内容（该函数应为 void）。

void readEmail(string& email) //reads in the email id provided
{
    cout << "Enter an email address: ";
    cin >> email;
}

int main() {
    string e, p;
    readEmail(e);
    checkEmail();
    return 0;
}

但是如果要返回值，则不需要参数，但需要将返回值赋予变量。

string readEmail() //reads in the email id provided
{
    cout << "Enter an email address: ";
    cin >> email;
    return email;
}
int main() {
    string e = readEmail();
    checkEmail();
    return 0;
}