generating random letter strings c++ code example

Example 1: getting a random letter in c++

char c;
    int r;

    srand (time(NULL));    // initialize the random number generator
    for (i=0; i<num; i++)
    {    r = rand() % 26;   // generate a random number
          c = 'a' + r;            // Convert to a character from a-z
          cout << c;
    }

Example 2: random string c++

#include <string>

string  gen_random(int len) {
    string s;
    static const char alphanum[] =
        "0123456789"
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz";

    for (int i = 0; i < len; ++i) {
        s += alphanum[rand() % (sizeof(alphanum) - 1)];
    }

    return s;
}