How can you get a "x" element from rand()?

I have a rand number generator. Now my question is how do I get for instance the first/second/third/fourth digit of the generated random number. Implementing this so the user can use a hint when guessing the number.

ex: result: 1234

hint 1: second number 2

hint 2: fourth number 4

Whats the best way to tackle this? I've been thinking to convert the string to an char array but that won't work I guess.

Correct me if my way of asking this questions is very bold.

int nummer = 4; 
std :: string result = "";

for (int i = 0; i < nummer; i++) 
{
    result.push_back(rand()%10 + '0'); 
}