Strange while loop behavior

问题

How is it that when I uncomment "//cout << current << endl;" in the code below, it works?

#include <iostream>
#include <float.h>

using namespace std;

int main()
{
  char divider = 2;
  float power = 1;
  float number = 1;
  float current = number + power;
  cout.precision(1024);
  // Divide until rounded off
  while(current != number)
  {
    power /= divider;
    current = number + power;
    //cout << current << endl;
  }

  cout << power * divider << endl;
  cout << FLT_EPSILON << endl;
}

The code above prints:

1.40129846432481707092372958328991613128026194187651577175706828388979108268586060148663818836212158203125e-45
1.1920928955078125e-07

But after uncommenting the line "//cout << current << endl;" it prints:

1.5
1.25
1.125
1.0625
1.03125
1.015625
1.0078125
1.00390625
1.001953125
1.0009765625
1.00048828125
1.000244140625
1.0001220703125
1.00006103515625
1.000030517578125
1.0000152587890625
1.00000762939453125
1.000003814697265625
1.0000019073486328125
1.00000095367431640625
1.000000476837158203125
1.0000002384185791015625
1.00000011920928955078125
1
1.1920928955078125e-07
1.1920928955078125e-07

Which is correct, but why doesn't it work without that line?

I use the Android app with ID "com.duy.c.cpp.compiler" version "1.2.4-armeabi-v7a".

回答1:

This is just my guess but from what I see when you comment cout << current << endl your program does the calculus but the only thing that will print on your screen are the 2 count at the end of your program so the value of power * diviser and the value of flt-epsilon.

On the other hand, if you uncomment it your program prints every result of the calculus done in the while loop so that's why it changes a lot what you see (because in the while loop every time you will divide power and add it to current it will print the result and so on until the condition is reached).

I hope that my explanations were clear enough ^^