Question

I’ve long been under the impression that goto should never be used if possible.

However, while perusing libavcodec (which is written in C) the other day, I was surprised to notice multiple uses of it.

Is it ever advantageous to use goto in a language that supports loops and functions? If so, why? Please provide a concrete example that clearly justifies the use of a goto.

Answer 1

There are a few reasons for using the ‘goto’ statement that I’m aware of (some have spoken to this already):

Cleanly exiting a function

Often in a function, you may allocate resources and need to exit in multiple places. Programmers can simplify their code by putting the resource cleanup code at the end of the function, and all ‘exit points’ of the function would goto the cleanup label. This way, you don’t have to write cleanup code at every ‘exit point’ of the function.

Exiting nested loops

If you’re in a nested loop and need to break out of all loops, a goto can make this much cleaner and simpler than break statements and if-checks.

Low-level performance improvements

This is only valid in perf-critical code, but goto statements execute very quickly and can give you a boost when moving through a function. This is a double-edged sword, however, because a compiler typically cannot optimize code that contains gotos.

Note that in all these examples, gotos are restricted to the scope of a single function.