From:	wivey AT ix DOT netcom DOT com (William H. Ivey)
Newsgroups:	comp.lang.c++,comp.os.msdos.djgpp,rec.games.programmer
Subject:	Re: pointer to function ??
Date:	25 Feb 1998 00:32:24 GMT
Organization:	Netcom
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References:	<6c7ltq$ms1$1 AT o DOT online DOT no> <6c7u5l$mub$2 AT news DOT ox DOT ac DOT uk> <01bd4107$bba0dc60$77111111 AT jfisher DOT team17 DOT com>
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To:	djgpp AT delorie DOT com
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In <01bd4107$bba0dc60$77111111 AT jfisher DOT team17 DOT com> "James E Fisher"
<James DOT Fisher AT team17 DOT com> writes: 
>
>The first idea of a pointer to the code is the fastest way as there is
>only one call to the required function (after the address of the
>function has been fetched).  Using a SWITCH statement is slower as it
>can end up as a list of IF() statements by the compiler.

Actually, if the switch contains more than a few case statements, it
will probably end up as a table of some sort. (In the simplest case,
where the key value can be manipulated into an index, a switch is
pretty darn fast.) But, you're right, where appropriate, a function
pointer is faster.


>You also need to think about debugging.  Using the pointer to a
>function is much cleaner to debug than having to wade through switch
>statements.

Only if your debugger can resolve the current contents of the pointer
into a meaningful function name for you. Otherwise, the switch is
clearer - you can put a break point in every case and see which one
gets called.-Wm

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