Posts Tagged ‘ternary operator’

Efficient C Tips #6 – Don’t use the ternary operator

Wednesday, February 18th, 2009 Nigel Jones

I have to confess that I like the ternary operator. K&R obviously liked it, as it is heavily featured in their seminal work. However after running experiments on a wide range of compilers I have concluded that with the optimizer turned on, you are better off with a simple if-else statement. Thus next time you write something like this:

y = (a > b) ? c : d;

be aware that as inelegant as it is in comparison, this will usually compile to better code:

if (a > b)
 y = c;
 y = d;

I find this frustrating, as I’ve consumed 8 lines doing what is more easily and elegantly performed in 1 line.

I can’t say that I have any particular insight as to why the ternary operator performs so poorly. Perhaps if there is a compiler writer out there, they could throw some light on the matter?

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