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Groups > comp.lang.c > #70150

Re: Issues with array, strlen, etc

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On 9/10/2015 4:38 AM, Richard Heathfield wrote:
> [...]
> In this loop:
>
> for(x; y; z)
> {
>    the_loop_body;
> }
>
> x is only executed once, at the beginning. y, z, and the_loop_body are
> executed once *per loop iteration*. [...]

     Richard isn't wrong very often, but he's wrong this time.

     x is executed once; Richard is right.

     y is executed either (1) the same number of times as
the_loop_body or (2) one more time than the_loop_body.

     z is executed either (2) the same number of times as
the_loop_body or (1) one fewer time than the_loop_body.

     Case (2) might be considered the "normal" case, when
the loop terminates by the action of the `for' part alone.
In this case, y precedes and z follows each the_loop_body
execution, and y executes one additional time (when it
evaluates to false and stops the loop).

     Case (1) holds when the_loop_body itself terminates the
loop, by executing a `break' or `return' or `goto' or the
like.  In this case, y precedes each the_loop_body execution
and z follows each one except the last.

     Caveat: All the above presumes that none of x,y,z, or
the_loop_body invokes undefined behavior, in which case
there's no telling what might happen.

-- 
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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Issues with array, strlen, etc Alla _ <modelling.data@gmail.com> - 2015-09-07 10:47 -0700
  Re: Issues with array, strlen, etc James Kuyper <jameskuyper@verizon.net> - 2015-09-07 14:47 -0400
  Re: Issues with array, strlen, etc bartekltg <bartekltg@gmail.com> - 2015-09-07 22:03 +0200
  Re: Issues with array, strlen, etc Paul N <gw7rib@aol.com> - 2015-09-07 13:08 -0700
  Re: Issues with array, strlen, etc Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-07 22:55 +0100
    Re: Issues with array, strlen, etc Rosario19 <Ros@invalid.invalid> - 2015-09-08 07:59 +0200
      Re: Issues with array, strlen, etc Rosario19 <Ros@invalid.invalid> - 2015-09-08 08:05 +0200
  Re: Issues with array, strlen, etc Barry Schwarz <schwarzb@dqel.com> - 2015-09-07 20:35 -0700
  Re: Issues with array, strlen, etc Alla _ <modelling.data@gmail.com> - 2015-09-08 01:08 -0700
    Re: Issues with array, strlen, etc Keith Thompson <kst-u@mib.org> - 2015-09-08 09:04 -0700
      Re: Issues with array, strlen, etc Alla _ <modelling.data@gmail.com> - 2015-09-10 01:22 -0700
        Re: Issues with array, strlen, etc Richard Heathfield <rjh@cpax.org.uk> - 2015-09-10 09:38 +0100
          Re: Issues with array, strlen, etc Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-09-10 07:34 -0400
            Re: Issues with array, strlen, etc David Brown <david.brown@hesbynett.no> - 2015-09-10 13:47 +0200
              Re: Issues with array, strlen, etc Richard Heathfield <rjh@cpax.org.uk> - 2015-09-10 13:11 +0100
          Re: Issues with array, strlen, etc Keith Thompson <kst-u@mib.org> - 2015-09-10 10:21 -0700
        Re: Issues with array, strlen, etc Geoff <geoff@invalid.invalid> - 2015-09-10 10:42 -0700
  Re: Issues with array, strlen, etc Alla _ <modelling.data@gmail.com> - 2015-09-08 01:11 -0700
    Re: Issues with array, strlen, etc Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-08 09:51 +0100
      Re: Issues with array, strlen, etc Alla _ <modelling.data@gmail.com> - 2015-09-08 02:39 -0700

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