Operations between float

[tasos g]

Hello,

I have a problem regarding to float's operations. I have the following loop:

////////////////////////////////////////////////////
x=(float)0.0;
for (i=0; i<262144; i++)
{
x=x+(1.0*3.814697265);
}
////////////////////////////////////////////////////
 

The final value of x must be 1,000,000 but it isn't. Does anyone know why??
thanks

[sicarie]

Yeah. Run this:

#include <iostream>
using namespace std;
 
int main()
{
   float x=0.0;
   int i_limit = 0;
   for (int i=0; i<262144; i++)
   {
      x=x+(1.0*3.814697265);
      if (i_limit < 5)
      {
         cout << x << << endl;
      }
      i_limit++;
   }
 
   return 0;
}

And then do the first five calculations by hand. Do you see anything interesting?

[weaknessforcats]

And keep in mind that a float has only 6 significant figures.