get a random line example

//http://www.youtube.com/user/thecplusplusguy
#include <iostream> //for write out (cout)
#include <fstream>  //for file handling (ifstream)
#include <vector>       //for store the lines   (vector)
#include <string>       //for store the strings
#include <ctime>        //for seed the random number generator (time(0))
#include <cstdlib>  //for random number generator (rand)
using namespace std;

int main()
{
    char buf[500]; //max 500 character/line
    ifstream in("example.txt"); //read the example.txt file
    vector<string> lines;   //create a vector, which contain strings
    srand(time(NULL));  //seed the random number generator
    //read all lines to the vector
    while(!in.eof())    //while we are not the end of the file
    {
        in.getline(buf,500);    //read a line to the buf (max 500 character, from in, to buf)
        lines.push_back(buf);   //push to the end of the lines vector
    }
    in.close(); //close the file, we don't need it anymore
    for(int i=0;i<10;i++)   //get 10 random number
    {
        int randline=rand()%(lines.size()-1);   //generate a random number, I use the -1 for the size, because it starts from 1 (if the vector 20 long, the max
        //number you get randomly is 20, but the biggest index is 19)
        cout << lines[randline] << endl;    //write out the line
    }
    return 0;
}

/*
solution 2, without read it to the memory
#include <iostream> //for write out (cout)
#include <fstream>  //for file handling (ifstream)
#include <ctime>        //for seed the random number generator (time(0))
#include <cstdlib>  //for random number generator (rand)
using namespace std;

int main()
{
    char buf[500]; //max 500 character/line
    ifstream in("example.txt"); //read the example.txt file
    int lines=0;
    srand(time(NULL));  //seed the random number generator
    //read all lines to the vector
    while(!in.eof())    //while we are not the end of the file
    {
        in.getline(buf,500);    //read a line to the buf (max 500 character, from in, to buf)
        lines++;
    }
    for(int i=0;i<10;i++)   //get 10 random number
    {
        in.clear();
        in.seekg(0,ios::beg);

        int randline=rand()%(lines-1)+1;    //generate a random number, I use the -1 for the size, because it starts from 1 (if the vector 20 long, the max
        //number you get randomly is 20, but the biggest index is 19)
        for(int i=0;i<randline;i++)
        {
            in.getline(buf,500);

        }
        cout << buf << endl;
    }
    in.close(); //close the file, we don't need it anymore
    return 0;
} */