[Solved] Need explanation of an expression

Question

At first glance, this appears to simplify to

if (a == 0)
    a = b;

However, if a is a NaN, this simplification gives different results. Any comparison with a NaN is false, so the more complicated expression will assign b to a if a is zero or a NaN.

Accepted Answer

At first glance, this appears to simplify to

if (a == 0)
    a = b;

However, if a is a NaN, this simplification gives different results. Any comparison with a NaN is false, so the more complicated expression will assign b to a if a is zero or a NaN.