Сравнение строк файла с введенными пользователем

#include <iostream>
#include <string>
#include <fstream>
#include <cstdio>
 
using namespace std;
 
void UserLoggin(string ,  string );
void EnterFild(string &, string &);
void DisplayMenu();
void AdminMenu();
void IsUserloginTrue();
 
int main() {
    string userlogin;
    string userpassword;
 
    DisplayMenu();
    UserLoggin(userlogin, userpassword);
 
    return 0;
}
 
void EnterFild(string &userlogin, string &userpassword) {
    cout << "Enter the login: ";
    cin >> userlogin;
 
    cout << "Enter the password: ";
    cin >> userpassword;
}
 
void Register() {
    string userlogin, userpassword;
 
    EnterFild(userlogin, userpassword);
 
    ofstream outFile;
    outFile.open("program.txt", ios_base::app);
    outFile << userlogin << " " << userpassword << endl;
    outFile.close();
 
    cout << "\n\n";
}
 
void UserLoggin(string userlogin, string userpassword) {
    string    loginAdministrator = "Admin";
    string passwordAdministrator = "Admin";
 
    EnterFild(userlogin, userpassword);
 
    if (userlogin == loginAdministrator && userpassword == passwordAdministrator) {
        cout << "\nYou have been entered as administrator." << endl;
    }
    else {
        for (int verify = 0; verify < 3; verify++) {
            cout << "\nUncorrect login or password.\n\tAttempts to enter left " << 3 - verify << endl;
 
            EnterFild(userlogin, userpassword);
            if (userlogin == loginAdministrator && userpassword == passwordAdministrator) {
                cout << "\nYou have been entered as administrator." << endl;
                cout << " - DISPLAY USERS: " << endl;
                AdminMenu();
                break;
            }
 
            if (verify == 2) {
                cout << "\n\nAccess denied!The number of attempts is limited!\n\n\n" << endl;
                exit(EXIT_SUCCESS);
            }
        }
    }
}
 
void AdminMenu() {
    ifstream insidFile("program.txt", ios_base::in);
    string line;
 
    if (insidFile.is_open()) {
        int qtyuser = 1;
        while (!insidFile.eof()) {
            getline(insidFile, line);
            cout << "\t#" << qtyuser++ << ": " << line << endl;
        }
    }
    else {
        cerr << "Error, couldn't be opened the file." << endl;
        exit(EXIT_FAILURE);
    }
}
 
void IsUserloginTrue() {
    ifstream isUserloginTrue("program.txt", ios_base::in);
    string symbol, find;
 
    if (isUserloginTrue.is_open()) {
        while (!isUserloginTrue.eof()) {
 
        }
    }
    else {
        cerr << "Error, couldn't be opened the file." << endl;
        exit(EXIT_FAILURE);
    }
}
 
void DisplayMenu() {
    string username, userpassword;
    int command = 0;
 
    do {
        cout << #include <iostream>
#include <string>
#include <fstream>
#include <cstdio>
 
using namespace std;
 
void UserLoggin(string ,  string );
void EnterFild(string &, string &);
void DisplayMenu();
void AdminMenu();
void IsUserloginTrue();
 
int main() {
    string userlogin;
    string userpassword;
 
    DisplayMenu();
    UserLoggin(userlogin, userpassword);
 
    return 0;
}
 
void EnterFild(string &userlogin, string &userpassword) {
    cout << "Enter the login: ";
    cin >> userlogin;
 
    cout << "Enter the password: ";
    cin >> userpassword;
}
 
void Register() {
    string userlogin, userpassword;
 
    EnterFild(userlogin, userpassword);
 
    ofstream outFile;
    outFile.open("program.txt", ios_base::app);
    outFile << userlogin << " " << userpassword << endl;
    outFile.close();
 
    cout << "\n\n";
}
 
void UserLoggin(string userlogin, string userpassword) {
    string    loginAdministrator = "Admin";
    string passwordAdministrator = "Admin";
 
    EnterFild(userlogin, userpassword);
 
    if (userlogin == loginAdministrator && userpassword == passwordAdministrator) {
        cout << "\nYou have been entered as administrator." << endl;
    }
    else {
        for (int verify = 0; verify < 3; verify++) {
            cout << "\nUncorrect login or password.\n\tAttempts to enter left " << 3 - verify << endl;
 
            EnterFild(userlogin, userpassword);
            if (userlogin == loginAdministrator && userpassword == passwordAdministrator) {
                cout << "\nYou have been entered as administrator." << endl;
                cout << " - DISPLAY USERS: " << endl;
                AdminMenu();
                break;
            }
 
            if (verify == 2) {
                cout << "\n\nAccess denied!The number of attempts is limited!\n\n\n" << endl;
                exit(EXIT_SUCCESS);
            }
        }
    }
}
 
void AdminMenu() {
    ifstream insidFile("program.txt", ios_base::in);
    string line;
 
    if (insidFile.is_open()) {
        int qtyuser = 1;
        while (!insidFile.eof()) {
            getline(insidFile, line);
            cout << "\t#" << qtyuser++ << ": " << line << endl;
        }
    }
    else {
        cerr << "Error, couldn't be opened the file." << endl;
        exit(EXIT_FAILURE);
    }
}
 
void IsUserloginTrue() {
    ifstream isUserloginTrue("program.txt", ios_base::in);
    string symbol, find;
 
    if (isUserloginTrue.is_open()) {
        while (!isUserloginTrue.eof()) {
                     //проверка
        }
    }
    else {
        cerr << "Error, couldn't be opened the file." << endl;
        exit(EXIT_FAILURE);
    }
}
 
void DisplayMenu() {
    string username, userpassword;
    int command = 0;
 
    do {
        cout << "1. Log in system" << endl;
        cout << "2. Registration" << endl;
        cout << "3. Exit" << endl;
        cout << "\tPlease select your option(1-3): ";
        cin >> command;
 
        switch (command) {
        case 1: UserLoggin(username, userpassword); break;
        case 2: Register(); break;
        case 3: exit(0); break;
        }
    } while (command != 3);
}
 
 << endl;
        cout << "2. Registration" << endl;
        cout << "3. Exit" << endl;
        cout << "\tPlease select your option(1-3): ";
        cin >> command;
 
        switch (command) {
        case 1: UserLoggin(username, userpassword); break;
        case 2: Register(); break;
        case 3: exit(0); break;
        }
    } while (command != 3);
}