#include <iostream>
#include <ctime>
#include <random>
#include <string>
#include <fstream>

using namespace std;

string random_string(size_t length )
{
    static const string alphabet = "abcdefghijklmnopqrstuvwxyz" ;
    static default_random_engine rng( time(nullptr) ) ;
    static uniform_int_distribution<size_t> distribution( 0, alphabet.size() - 1 ) ;

    string str ;
    while( str.size() < length ) str += alphabet[ distribution(rng) ] ;
    return str ;
}

int main()
{
    srand (time(NULL));
    ofstream myfile;
    myfile.open ("string.txt");

    //for( size_t i = 10 ; i < 40 ; i += 3 ) cout << random_string(i) << '\n' ;

    for(int k = 0; k < 10000; k++)
    {
        int range = rand() % 20 + 2;
        myfile << random_string(range) << '\n';
    }
    myfile.close();
}