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

       by Nigel Jones

       原文: http://embeddedgurus.com/stack-overflow/2009/02/efficient-c-tips-6-dont-use-the-ternary-operator/

        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;}else{    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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