Implementation of a Falling Matrix

// C++ program for implementation of falling matrix.
#include<iostream>
#include<string>
#include<thread>
#include<cstdlib>
#include<ctime>
#include<chrono>

// Width of the matrix line
const int width = 70;

// Defines the number of flips in Boolean Array 'switches'
const int flipsPerLine = 5;

// Delay between two successive line print
const int sleepTime = 100;

using namespace std;

int main()
{
    int i = 0, x = 0;

    // srand initialized with time function
    // to get distinct rand values at runtime
    srand(time(NULL));

    // Used to decide whether to print
    // the character in that particular iteration
    bool switches[width] = {0};

    // Set of characters to print from
    const string ch = "1234567890qwertyuiopasdfghjkl"
                      "zxcvbnm,./';[]!@#$%^&*()-=_+";
    const int l = ch.size();

    // Green font over black console, duh!
    system("Color 0A");

    // Indefinite Loop
    while (true)
    {
        // Loop over the width
        // Increment by 2 gives better effect
        for (i = 0; i < width; i += 2)
        {
            // Print character if switches[i] is 1
            // Else print a blank character
            if (switches[i])
                cout << ch[rand() % l] << " ";
            else
                cout << "  ";
        }

        // Flip the defined amount of Boolean values
        // after each line
        for (i = 0; i != flipsPerLine; ++i)
        {
            x = rand() % width;
            switches[x] = !switches[x];
        }

        // New Line
        cout << endl;

        // Using sleep_for function to delay,
        // chrono milliseconds function to convert to milliseconds
        this_thread::sleep_for(chrono::milliseconds(sleepTime));
    }
    return 0;
}