can I compare two fractions if both have denominator with power of 2

Question

I know it's not "possible" to compare two real, but is it true for real which have denominator power of 2

Is equality of this king always return true

if( 3/4. == 6/8. ) {}

Answer 1

This kind of expression should always evaluate to true, with a few caveats:

• The numerators don't exceed 2^52; otherwise they'll lose precision.
• The denominators don't exceed the range provided by double-precision.
• You must be working on a platform that uses radix-2 floating-point (which is basically all modern machines).