random string generator

rand_string_gen.cpp

#include <iostream>
using namespace std;
static char *rand_string(char *str, size_t size)
{
    const char charset[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJK...";
    if (size) {
        --size;
        for (size_t n = 0; n < size; n++) {
            int key = rand() % (int) (sizeof charset - 1);
            str[n] = charset[key];
        }
        str[size] = '\0';
    }
    return str;
}
int main() {
	// your code goes here
	char s[]="varun";
	rand_string(s,6);
	cout<<s;
	
	return 0;
}