Carl's Bank

#include <iostream>
#include <iomanip>
#include <limits>
using namespace std;
//Global Variables
//Global string arrays
string USERNAME[9999] = { "Doodle", "Kinchi", "Multi" }; //starting usernames
string PASSWORD[9999] = { "54476", "12345", "Airplane" }; // starting passwords
//Global float balance
float balance[9999] = {5000, 4000, 3000}; //starting respective balance
//Global user number (for arrays)
int userNo;
int userMemory = 3; //start at fourth term

//Prototype Variables
//Account Functions
bool login(void);
void registerAccount(void);
//Action
float withdraw(void);
float deposit(void);
void check(void);
void cancel(void);
void exitProgram(void);
//Tab
void tab(void);
void tab2(void);
void tab3(void);

main(){
    bool exit = false;
    tab();tab3();
    tab2();cout << "Welcome to Carl's Bank";
    tab();tab3();
    cout << endl;
    while (exit != true){
        string input;
        do {
            tab();tab3();
            tab2();cout << "Carl's Bank: Home Menu";
            tab();tab3();
            cout << endl;
            tab2();
            cout << "[1] Login";
            cout << endl;
            cout << endl;
            tab2();
            cout << "[2] Register";
            cout << endl;
            cout << endl;
            tab2();
            cout << "[3] Exit";
            cout << endl;
            cout << endl;
            cout << endl;
            tab2();
            cout << "Input: ";
            cin >> input;
        } while (!(input == "1" || input == "2" || input == "3"));
        if (input == "1"){
            bool valid = login();
            if (valid){
                tab2();
                cout << "Greetings, " << USERNAME[userNo];
                bool cancel = false;
                while (!(cancel)){
                    string input2;
                    do {
                        cout << endl;
                        tab();tab3();
                        tab2();
                        cout << "Carl's Bank: Action";
                        tab();tab3();
                        cout << endl;
                        tab2();
                        cout << "[1] Deposit Money";
                        cout << endl;
                        cout << endl;
                        tab2();
                        cout << "[2] Withdraw Money";
                        cout << endl;
                        cout << endl;
                        tab2();
                        cout << "[3] Check Balance";
                        cout << endl;
                        cout << endl;
                        tab2();
                        cout << "[4] Log out";
                        cout << endl;
                        cout << endl;
                        cout << endl;
                        tab2();
                        cout << "Input: ";
                        cin >> input2;
                    } while (!(input2 == "1" || input2 == "2" || input2 == "3" || input2 == "4"));
                    if (input2 == "1"){
                        balance[userNo] += deposit();
                    }
                    else if (input2 == "2"){
                        balance[userNo] -= withdraw();
                    }
                    else if (input2 == "3"){
                        check();
                    }
                    else if (input2 == "4"){
                        cancel = true;
                    }
                }
            }
        }
        else if (input == "2"){
            registerAccount();
        }
        else if (input == "3"){
            exitProgram();
        }
    }
}

//login function
bool login(void){
    string username;
    string password;
    cout << endl;
    cout << endl;
    tab();tab3();
    tab2();
    cout << "Carl's Bank: Login";
    tab();tab3();
    cout << endl;
    tab2();
    cout << "Enter Username: ";
    cin >> username;
    cout << endl;
    tab2();
    cout << "Enter Password: ";
    cin >> password;
    cout << endl;

    for (int i = 0; i < 100; i++){
        if ((username.compare(USERNAME[i]) == 0) &&
            (password.compare(PASSWORD[i]) == 0)){
                userNo = i;
                return true;
        }
    }
    return false;
}

float withdraw(void){
    float x;
    bool validInput = false;
    x = -1;
    cout << endl;
    do {
        cout << endl;
        tab2();
        cout << "How much do you want to withdraw? ";
        cin >> x;
        if (!(validInput = cin.good())){
            cin.clear();
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
        }
    } while (!(x >= 0 && x <= balance[userNo]));
    cout << endl;
    tab2();
    cout << setprecision(2) << fixed;
    cout << "Php " << x << " has been reduced from your account . . . ";
    cout << endl;
    system("pause");
    return x;
}

float deposit(void){
    float x;
    bool validInput = false;
    cout << endl;
    do {
        cout << endl;
        tab2();
        cout << "How much do you want to deposit? ";
        cin >> x;
        if (!(validInput = cin.good())){
            cin.clear();
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
        }
    } while (!(x >= 0) && !validInput);
    cout << endl;
    tab2();
    cout << setprecision(2) << fixed;
    cout << "Php " << x << " has been added to your account . . . ";
    cout << endl;
    system("pause");
    return x;
}

void check(void){
    cout << endl;
    cout << endl;
    tab2();
    cout << setprecision(2) << fixed;
    cout << "Your balance: Php " << balance[userNo];
    cout << endl;
    system("pause");
}

void tab(void){
    cout << endl;
    for (int a = 0; a <= 15; a++){
        cout << " ";
    }
}

void tab2(void){
    for (int a = 0; a <= 17; a++){
        cout << " ";
    }
}

void tab3(void){
    for (int a = 0; a <= 30; a++){
        cout << "=";
    }
    cout << endl;
}

void registerAccount(void){
    string input, input2;
    float input3;
    int b = 0, c, d;
    tab();tab3();
    tab2();
    cout << "Carl's Bank: Register";
    tab();tab3();
    cout << endl;
    do {
        d = 0;
        tab2();
        cout << "Enter Username: "; cin >> input;
        cout << endl;
        cout << endl;
        for (c = 0; c <= userMemory-1; c++){
            if (input == USERNAME[c]){
                d = 1;
            }
            if (d == 1){
                b = 0;
            }
            else b = 1;
        }
        if (b == 0){
            tab2();
            cout << "This username has already been used . . . ";
            cout << endl;
            cout << endl;
            system("pause");
        }
    } while(b == 0);
    tab2();
    cout << "Enter Password: "; cin >> input2;
    cout << endl;
    cout << endl;
    bool validInput = false;
    do {
        tab2();
        cout << "Deposit Balance: "; cin >> input3;
        cout << endl;
        if (!(validInput = cin.good())){
            cin.clear();
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
        }
    } while (input3 <= 0 && !validInput);
    USERNAME[userMemory] = input;
    PASSWORD[userMemory] = input2;
    balance[userMemory] = input3;
    userMemory++;
}

void exitProgram(void){
    cout << endl;
    cout << endl;
    tab2();
    cout << "Ending program . . . ";
    cout << endl;
    cout << endl;
    abort();
}