Reliable Representation of Integers in Floats

FloatPrecisionTest.cc

#include <iostream>

int main() {
  int n = 0;
  for (long w=1; w<=10000000000000L; w*=10) {
    int k = 0;
    for (int i=0; i<1000000; i++) {
      long p = (long)(rand()%w);
      long q = (float) p;
      if (p != q) k++;
    }    
    std::cout << "\n";
    std::cout << n++ << "\n";
    std::cout << w-1 << "\n";
    std::cout << (long)(rand()%w) << "\n";
    std::cout << k << "\n";
  }
}

FloatPrecisionTest.java

class FloatPrecisionTest {
  public static void main(String[] args) {
    int n = 0;
    for (long w=1; w<=10000000000000L; w*=2) {
      int k = 0;
      for (int i=0; i<1000000; i++) {
        long p = (long)(Math.random()*w);
        long q = (long)(float) p;
        if (p != q) k++;
      }
      System.out.println();
      System.out.println(n++);
      System.out.println(w-1);
      System.out.println((long)(Math.random()*w));
      System.out.println(k);
    }   
  }
}