Question

Possible Duplicate:
Addition of Double values inconsistent

int x = 0;
float n = 0;
while ( n != 1 ) {
n += 0.1;
++x;
}

I wonder Why this loop is infinite?

Answer 1

0.1 cannot be represented exactly in floating-point:

printf("%.16f\n", 0.1f);

displays:

0.1000000014901161

So n will never be exactly equal to 1.

As @sirlak says in comments below, it’s almost never correct to test floating-point variables for equality like this.