Four digit random number without digit repetition

Question

Is there any way you can have a 4 digit number without repetition - e.g. not 1130 but 1234? I read std::random_shuffle could do this b

Answer 1

One possibility is to generate a string containing the digits, and to use the C++14 function std::experimental::sample()

#include 
#include 
#include 
#include 
#include 

int main() {
std::string in = "0123456789", out;
do {
    out="";
    std::experimental::sample(in.begin(), in.end(), std::back_inserter(out), 4, std::mt19937{std::random_device{}()});
    std::shuffle(out.begin(), out.end(), std::mt19937{std::random_device{}()});
  } while (out[0]=='0');
  std::cout << "random four-digit number with unique digits:"  << out << '\n';
}

Edit:

Changed to prevent a result that starts with a 0. Hat tip to @Bathsheba who indicated that this could be a problem.