Re: on an analogy for verifying whether another digit fits (into an unsigned type)

From	Bart <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: on an analogy for verifying whether another digit fits (into an unsigned type)
Date	2022-01-20 10:05 +0000
Organization	A noiseless patient Spider
Message-ID	<ssbc4i$9a0$1@dont-email.me> (permalink)
References	(6 earlier) <C0ZFJ.134459$Gco3.62864@fx01.iad> <ss9u3b$jdr$1@dont-email.me> <X8%FJ.28$rU.26@fx34.iad> <ssa342$rih$1@dont-email.me> <87tudz2his.fsf@bsb.me.uk>

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On 20/01/2022 03:49, Ben Bacarisse wrote:
> Bart <bc@freeuk.com> writes:
> 
>> But in the case of strtoull, there are other issues with it:
>>
>> * Not all compilers may recognise it
> 
> It's almost always library issue, not a compiler issue.  Any
> implementation (compiler + library) that does not have it is a poor one
> since it's been standard for a long time now.
> 
>> * The performance depends on the library used
>>
>> Using your own routine for this simple task eliminates those variables.
>>
>> The timing I quoted was the worst:
>>
>> * gcc/strtoull on Windows: 2.8 seconds (for 1M conversions)
>>
>> * gcc/strtoull on WSL: 0.6 seconds
>>
>> * gcc/_strtoui64 on Windows (in msvcrt): 0.7 seconds
> 
> You keep citing figures with little useful information.  What length
> numbers?  What are these various (apparently slow) implementation of
> strtoull that you have managed to find?  Calling them gcc/strtoull is
> not helpful.
>

The full program is here:

https://github.com/sal55/langs/blob/master/parseull.c

You need to uncomment the routine you want in the inner loop. The 
numbers are the ones generated with BM's program. Timings are elapsed 
time from running the program, measured externally.

> For 10^6 numbers with, on average, 18.3 digits, the strtoull on a recent
> Ubuntu install (glibc 2.34) does the conversions in 0.042 seconds
> (i5-8265U CPU).  Is your machine really more than 10 times slower than
> my laptop?

Sorry, that was my mistake: it's 10^7 conversions (originally 10^6 in 
the C++ code but that was too quick to easily measure).

>> * My parseull routine on Windows: 0.28/0.35 seconds (with/without
>> length)
> 
> This one probably doesn't do the same job, so it's not a direct
> comparison.

It was supposed to do the same job as BM's program: take a string 
containing only digits and convert them while checking for overflows.

Although mine won't allow leading zeros if the overflow check is to 
work; that would slow it down slightly to eliminate them.

Thread

on an analogy for verifying whether another digit fits (into an unsigned type) Meredith Montgomery <mmontgomery@levado.to> - 2022-01-15 23:27 -0300
  Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-16 18:44 +0000
    Re: on an analogy for verifying whether another digit fits (into an unsigned type) Meredith Montgomery <mmontgomery@levado.to> - 2022-01-17 09:48 -0300
      Re: on an analogy for verifying whether another digit fits (into an unsigned type) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-17 17:27 +0000
        Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-17 18:06 +0000
          Re: on an analogy for verifying whether another digit fits (into an unsigned type) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-17 20:59 +0000
            Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-18 01:01 +0000
        Re: on an analogy for verifying whether another digit fits (into an unsigned type) Meredith Montgomery <mmontgomery@levado.to> - 2022-01-28 22:15 -0300
          Re: on an analogy for verifying whether another digit fits (into an unsigned type) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-29 02:36 +0000
            Re: on an analogy for verifying whether another digit fits (into an unsigned type) Meredith Montgomery <mmontgomery@levado.to> - 2022-01-30 09:12 -0300
              Re: on an analogy for verifying whether another digit fits (into an unsigned type) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-30 15:13 +0000
  Re: on an analogy for verifying whether another digit fits (into an unsigned type) Öö Tiib <ootiib@hot.ee> - 2022-01-16 12:15 -0800
    Re: on an analogy for verifying whether another digit fits (into an unsigned type) Meredith Montgomery <mmontgomery@levado.to> - 2022-01-17 09:53 -0300
      Re: on an analogy for verifying whether another digit fits (into an unsigned type) Meredith Montgomery <mmontgomery@levado.to> - 2022-01-17 10:12 -0300
  Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-19 08:52 +0100
    Re: on an analogy for verifying whether another digit fits (into an unsigned type) Öö Tiib <ootiib@hot.ee> - 2022-01-19 06:08 -0800
      Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-19 16:31 +0100
        Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-19 18:02 +0100
          Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-19 18:27 +0000
            Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-19 19:44 +0100
              Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-20 08:08 +0100
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Öö Tiib <ootiib@hot.ee> - 2022-01-20 09:47 -0800
            Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-19 18:46 +0000
              Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-19 20:59 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-19 21:12 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-19 22:25 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-20 03:49 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-20 10:05 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-20 17:02 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-20 19:20 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-20 19:31 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-23 14:26 -0800
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-24 00:13 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2022-01-24 00:38 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-24 01:09 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-24 01:15 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-24 11:21 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-24 15:54 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-24 13:08 -0800
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-24 22:51 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-24 15:57 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-24 16:52 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Öö Tiib <ootiib@hot.ee> - 2022-01-24 10:17 -0800
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-24 18:23 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-24 13:15 -0800
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-24 11:51 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-23 17:38 -0800
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-24 11:22 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-24 15:51 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-24 22:03 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-24 15:33 -0800
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-25 00:09 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-24 21:14 -0800
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Manfred <invalid@invalid.add> - 2022-01-26 21:01 +0100
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bart <bc@freeuk.com> - 2022-01-26 20:53 +0000
                Re: on an analogy for verifying whether another digit fits (into an unsigned type) Manfred <noname@add.invalid> - 2022-01-27 03:42 +0100
  Re: on an analogy for verifying whether another digit fits (into an unsigned type) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-20 19:24 -0800
    Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-21 08:07 +0100
      Re: on an analogy for verifying whether another digit fits (into an unsigned type) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-21 06:01 -0800
        Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-21 17:59 +0100
          Re: on an analogy for verifying whether another digit fits (into an unsigned type) scott@slp53.sl.home (Scott Lurndal) - 2022-01-21 17:41 +0000
            Re: on an analogy for verifying whether another digit fits (into an unsigned type) Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-21 19:26 +0100
          Re: on an analogy for verifying whether another digit fits (into an unsigned type) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-21 17:12 -0800
    Re: on an analogy for verifying whether another digit fits (into an unsigned type) Meredith Montgomery <mmontgomery@levado.to> - 2022-01-28 22:25 -0300

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