doc hadj

#include <iostream>
#include <iomanip>
#include <string.h>
#include <math.h>
using namespace std;

int a, i, upperLimit, number = 1, step = 1;
bool mainchoice;
void data1() {

    int upperLimit, digit;
    cout << "Enter upper limit: ";
    cin >> upperLimit;

    for (int i = 1; i <= upperLimit; i++)
    {
        digit = i % 10;
        if (digit == 1 || digit == 2 || digit == 4 || digit == 8) {
            cout << i << " ";
        }
    }

}

void data2() {

    int upper_limit, digit;
    cout << "Enter upper limit: ";
    cin >> upper_limit;

    for (int i = 1; i <= upper_limit; i++) {
        digit = i % 4;
        if (digit == 1 || digit == 3)
            cout << i << " ";
    }

}

void data3() {


    cout << "Enter upper limit: ";
    cin >> upperLimit;

    upperLimit *= 2;
    int number = 1, i = 1;
    while (number <= upperLimit) {
        if (i % 2 == 1) {
            cout << number << " ";
        }
        else {
            cout << i + 2 << " ";
        }
        number += i;
        i++;
    }
}


void data4()

{
    int n;
    double sum = 0.0;
    cout << "Enter n: ";
    cin >> n;

    if (n <= 0) {
        cout << "Invalid input. Please enter a positive integer." << endl;
    }

    int i = 1;
    bool firstTerm = true; // determine if it's the first term in the series

    cout << "Sum of the series: ";

    do {
        if (!firstTerm) {
            cout << " + ";
        }
        else {
            firstTerm = false;
        }

        cout << i << "/" << i + 1;

        sum += static_cast<double>(i) / (i + 1);
        i++;
    } while (i <= n);

    cout << " = " << fixed << setprecision(3) << sum << endl;

}


void data5() {
    int num, digit;
    cout << "Enter a number: ";
    cin >> num;
    if (num == 0) {
        cout << "zero " << endl;
    }
    const char* words[] = { "zero ", "one ", "two ", "three ", "four ", "five ", "six ", "seven ", "eight ", "nine " };
    string reverseWords = "";

    while (num > 0) {
        digit = num % 10;
        num /= 10;
        reverseWords = words[digit] + reverseWords;
    }

    cout << "Output: " << reverseWords << endl;
}

int main() {
    while (mainchoice = true)
    {
    int choice = 0;

    cout << "Choose one:\n1. Sequence of 1, 2, 4, and 8 Generator\n2. Modulo 4\n3. Alternating Numbers\n4. '1 / 2 + 2 / 3 + 3 / 4 ...'\n5. Numbers to Words\n6. Exit. " << endl;
    cout << "Choice: ";
    cin >> choice;

    switch (choice)
    {
    case 1:
        system("cls");
        data1();
        cout << "\n\n\n";
        break;
    case 2:
        system("cls");
        data2();
        cout << "\n\n\n";
        break;
    case 3:
        system("cls");
        data3();
        cout << "\n\n\n";
        break;
    case 4:
        system("cls");
        data4();
        cout << "\n\n\n";
        break;
    case 5:
        system("cls");
        data5();
        cout << "\n\n\n";
        break;
    case 6:
        system("cls");
        cout << "Program Exited!";
        cout << "\n\n\n";
        return 0;
    default:
        cout << "Please Enter a valid option.";
        cout << "\n\n\n";
        break;
    }
}
            return 0;

}
/*(use for)
 Enter upper limit: 50
1 2 4 8 11 12 14 18 21 22 24 28 31 32 34 38 41 42 44 48

 (use for)
 Enter upper limit: 50
 1 3 9 13 18 19 22 24 30 34 39 40 43 45

 (use while)
 Enter upper limit: 50
 1 3 3 6 5 11 7 18 9 27 11 38 13 51 15 66 17 83 19

(use do while)
 Enter n: 10
sum of the series
 1/2+2/3+3/4+4/5+5/6+6/7+7/8+8/9+10/11 =. 7.980

 (use while loop)
 Enter a number: 2193
 Output
 three nine one two

 Enter a number: 1020
 Output
 zero two zero one
*/