Fibonacci code

// This is the Week 7 Quiz

// This program will tell you if a number between 1 and 100 are in the Fibonacci sequence.

// David Hawkins

//=============================================================================================//

#include <iostream>
#include <iomanip>

using namespace std;

void fibonacci(int); // This function tests the integer you choose against the fibonacci sequence and outputs the results
int numcheck(); // This function ensures that you you input an integer between 1 and 100
void goagain(); // This function lets you test different numbers.

//----------------------------------------MAIN------------------------------------------------//
int main()
{
    while (true)
    {
        int number;
        cout << setw(80) << setfill('*') << '*' << endl;
        cout << "This program will tell you whether or not an integer between 1 and\n100 is part of the Fibonacci Sequence.\n\n" << endl;
        cout << "What is your number?: ";
        number = numcheck();
        fibonacci(number);
        goagain();
    }
}

//------------------------------------numcheck----------------------------------------------//
int numcheck()
{
    int numchoice;
    int timer = 0; // I always use the "timer" variable to keep a program from looping endlessly.
    cin >> numchoice;
    cout << setw(80) << setfill('*') << '*' << endl;
    while (0 > numchoice || 100 < numchoice)
    {
        timer += 1;
        if (timer > 3)
            exit(0);
        else
        {
            cout << "Please choose a number between 0 and 100\nYou have " << 3 - timer << " attempts remaining\n\nWhat is your number?: ";
            cin >> numchoice;
            cout << setw(80) << setfill('*') << '*' << endl;
        }
    }
    return numchoice;
}

//---------------------------------fibonacci------------------------------------------------//
void fibonacci(int numtest)
{
    int fibonum1 = 1; // This variable is tested again the number you chose to verify if it is in the fibonacci sequence
    int fibonum2 = 0; // fibonum2 and fibonum3 are place holders to help move the fibonacci sequence forward.
    int fibonum3 = 1;
    int i;
    while (fibonum1 <= 100) // This while loop makes sure that all number in the fibonacci sequence are accounted for and also that the program doesn't calculate the forever.
    {
        if (fibonum1 == numtest)
        {
            break;
        }
        else // The statements in this block of code are what move the variable "fibonum1" through the fibonacci sequence.
        {
            fibonum1 = fibonum2 + fibonum3;
            fibonum2 = fibonum3;
            fibonum3 = fibonum1;
        }
    }
    if (fibonum1 == numtest)
    {
        cout << "Your number is in the Fibonacci sequence." << endl;
        cout << setw(80) << setfill('*') << '*' << endl;
    }
    else
    {
        cout << "Your number is NOT within the Fibonacci sequence." << endl;
        cout << setw(80) << setfill('*') << '*' << endl;
    }
}

//----------------------------goagain-------------------------------------------------//
void goagain()
{
    char cont;
    int timer = 1;
    cout << "would you like to go again?\ny or n?: ";
    cin >> cont;
    cont = tolower(cont);
    if (cont == 'y')
        system("CLS");
    else if (cont == 'n')
        exit(0);
    else
    {
        while (true)
        {
            cout << "USE CORRECT INPUTS\nyou have " << 3 - timer << " more attempts before exiting\nWould you like to go again?\nY or N?  ";
            cin >> cont;
            cont = tolower(cont);
            cout << endl;
            timer += 1;
            if (timer > 3)
                exit(0);
            else if ('y' == cont)
            {
                system("CLS");
                break;
            }
            else if ('n' == cont)
                exit(0);
        }
    }
}