C++ : 乱数生成

#include <time.h>
#include <iostream>

double randf() {
   return static_cast<double>(rand()) * (1.0 / (RAND_MAX+1));
}

size_t randi(size_t min, size_t max) {
  return min + static_cast<size_t>(rand()) % (max- min);
}

int main(void) {
  srand(time(NULL));
  for (int i = 0; i < 100; ++i) {
    std::cout << randf() << " ";
  }
  std::cout << std::endl;

  for (int i = 0; i < 100; ++i) {
    std::cout << randi(10, 20) << " ";
  }
  std::cout << std::endl;
  return 0;
}