C++ ifstream 只读取最后一行

Question

我正在开发一个允许用户注册帐户的程序。用户注册账号时，用户名和密码输出到文本文件“database.txt”.

如果用户忘记了密码，还可以选择通过输入用户名来搜索密码。我发现当 .txt 文件数据库中只有一个用户注册时，这可以正常工作。但是，当有多个用户时，忘记密码功能return无论搜索哪个用户名，都是最近注册用户的密码。

database.txt 看起来像这样：

user1 111
user2 222
user3 333

无论输入哪个用户找密码，函数总是return333，也就是最近注册用户的密码。我该如何解决这个问题，以便无论搜索哪个用户，都会输出他们的密码？

函数如下：

void forgot()
{   
int ch;
system("cls");
cout << "Forgotten? We're here to help." << endl;
cout << "Choose one of the options below: " << endl;
cout << "1. Forgot my password" << endl;
cout << "2. Forgot my username" << endl;
cout << endl;
cout << "Enter your choice: ";
cin >> ch;

switch(ch)
{
    case 1: // search for username to find password
    {
        int count = 0;
        string searchUser, su, sp;
        cout << "Enter your username: "; 
        cin >> searchUser;

        ifstream searchUserName("database.txt"); 
        while(searchUserName >> su >> sp)
        {
            if(su == searchUser)
            {
                count = 1;
            }
        }
        searchUserName.close();
        if(count == 1)
        {
            cout << "Account found!" << endl;
            cout << "Your password is: " << sp;
            cin.get();
            cin.get();
            system("cls");
            menu();
        }
        else 
        {
            cout << "Sorry, that user ID does not exist." << endl;
            cout << "Please contact our service team for more details." << endl;
            cin.get();
            cin.get();
            system("cls");
            menu();
        }
        break;
    }
    case 2: // search for password to find username
    {
        int count = 0;
        string searchPass, su2, sp2;
        cout << "Enter your password: "; 
        cin >> searchPass;

        ifstream searchPassword("database.txt");
        while(searchPassword >> su2 >> sp2)
        {
            if(sp2 == searchPass)
            {
                count = 1;
            }
        }
        searchPassword.close();
        if(count == 1)
        {
            cout << "Your password has been found." << endl;
            cout << "Your username is: " << su2;
            cin.get();
            cin.get();
            system("cls");
            menu();
        }
        else
        {
            cout << "Sorry, we couldn't find your password in our database." << endl;
            cout << "Please contact our team for more information." << endl; 
            cin.get();
            cin.get();
            system("cls");
            menu();
        }

        break;
    }
    default: 
        cout << "Invalid choice, please try again." << endl;
        system("cls");
        forgot();
}

}

Answer 1

在此处找到用户名后，您应该跳出 while 循环：

        while(searchUserName >> su >> sp)
        {
            if(su == searchUser)
            {
                count = 1;
                break; // add this
            }
        }

现在它将继续覆盖以前找到的用户名，直到 searchUserName >> su >> sp 不再是 true，在大多数情况下它会遇到 EOF。

程序的另一部分也有同样的问题

我个人会重写代码，使是否找到匹配密码的条件成为循环条件的一部分。

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