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Re: Sum using variadic macros

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On 14/12/2016 19:26, Thiago Adams wrote:
> On Wednesday, December 14, 2016 at 5:20:39 PM UTC-2, Bart wrote:

>> Why can't you calculate it at runtime during initialisation? Or does it
>> have to be used in array bound or switch-case expressions?
>
>
> Yes, I want to use in switch-case.
> Otherwise I would use some function address to work as a "ID".
>
> I suspect, I didn't check, that switch-cases are faster then if-elses because the compiler can create some table.

Yes, if the values are localised.

But good hash values would be spread out and over a wide range making 
the use of a jump table harder.

If the strings are small however, say 4 characters or less, I might just 
use the character codes directly: 'this'. Although you'd have to check 
what different compilers do with multi-character literals like this.

Presumably you are looking up a hashed string against a set of 
pre-calculated hash values. I think you might be better off with an 
actual hash table, if the switch statement can't use the hash values 
profitably.

-- 
Bartc

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Sum using variadic macros Thiago Adams <thiago.adams@gmail.com> - 2016-12-14 02:54 -0800
  Re: Sum using variadic macros Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-14 11:51 +0000
    Re: Sum using variadic macros David Brown <david.brown@hesbynett.no> - 2016-12-14 13:58 +0100
      Re: Sum using variadic macros Richard Heathfield <rjh@cpax.org.uk> - 2016-12-14 14:01 +0000
      Re: Sum using variadic macros Thiago Adams <thiago.adams@gmail.com> - 2016-12-14 08:05 -0800
        Re: Sum using variadic macros BartC <bc@freeuk.com> - 2016-12-14 19:20 +0000
          Re: Sum using variadic macros Thiago Adams <thiago.adams@gmail.com> - 2016-12-14 11:26 -0800
            Re: Sum using variadic macros BartC <bc@freeuk.com> - 2016-12-14 20:06 +0000
    Re: Sum using variadic macros Thiago Adams <thiago.adams@gmail.com> - 2016-12-14 05:25 -0800
      Re: Sum using variadic macros mark.bluemel@gmail.com - 2016-12-14 08:10 -0800
        Re: Sum using variadic macros Thiago Adams <thiago.adams@gmail.com> - 2016-12-14 08:23 -0800
          Re: Sum using variadic macros Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-14 11:32 -0800
      Re: Sum using variadic macros Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-14 16:26 +0000
        Re: Sum using variadic macros David Brown <david.brown@hesbynett.no> - 2016-12-14 19:09 +0100
          Re: Sum using variadic macros supercat@casperkitty.com - 2016-12-14 11:33 -0800
          Re: Sum using variadic macros Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-14 19:40 +0000

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