Re: What practice can get speed improvement in C++?

From	Martin Shobe <martin.shobe@yahoo.com>
Newsgroups	comp.lang.c++
Subject	Re: What practice can get speed improvement in C++?
Date	2015-08-05 08:53 -0500
Organization	A noiseless patient Spider
Message-ID	<mpt4e9$43u$1@dont-email.me> (permalink)
References	(1 earlier) <mpn80m$1tej$1@adenine.netfront.net> <bc4afec4-babe-46b1-83e4-fa3de87cfeb3@googlegroups.com> <mppslj$iam$1@adenine.netfront.net> <f76c748e-03ed-41ae-8e8c-6bd49b6f9f3c@googlegroups.com> <mpsggk$27e5$1@adenine.netfront.net>

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On 8/5/2015 3:12 AM, Juha Nieminen wrote:
> woodbrian77@gmail.com wrote:
>> This is interesting
>>
>> http://stackoverflow.com/questions/21946447/how-much-performance-difference-when-using-string-vs-char-array
>
> They are not doing the same thing. Formatted printing into a static buffer
> is not the same thing as building a dynamic string by appending stuff.
>
> If std::sprintf() is sufficient for the task at hand, then definitely
> use that. (After all, I did mention in my post that C I/O functions
> tend to be more efficient than the C++ equivalents.)
>

Just for fun, I run the tests above using Visual Studio 2013 (I used the 
default release options and _snprintf instead of snprintf. I also added 
a test for stringstream performance.) and got the following results.

Length is the length of the string in baseLocation. stream is the 
average time to build the filename using a stringstream. reserve is the 
average time using a string with a reserved buffer. string is using a 
string without using a reserved buffer. Array is the c-style array.

length stream  reserve string  array
12     8.6122  3.7423  4.4735  4.6979 microseconds
78     7.8117  3.7714  4.4523  6.3554 microseconds

Which I think provides evidence for the maxim about measuring.

Martin Shobe

Thread

What practice can get speed improvement in C++? fl <rxjwg98@gmail.com> - 2015-07-14 16:53 -0700
  Re: What practice can get speed improvement in C++? Barry Schwarz <schwarzb@dqel.com> - 2015-07-14 17:23 -0700
    Re: What practice can get speed improvement in C++? bartekltg <bartekltg@gmail.com> - 2015-07-15 15:10 +0200
      Re: What practice can get speed improvement in C++? JiiPee <no@notvalid.com> - 2015-07-16 05:00 +0100
        Re: What practice can get speed improvement in C++? Öö Tiib <ootiib@hot.ee> - 2015-07-16 01:04 -0700
          Re: What practice can get speed improvement in C++? JiiPee <no@notvalid.com> - 2015-07-16 16:48 +0100
            Re: What practice can get speed improvement in C++? JiiPee <no@notvalid.com> - 2015-07-16 16:52 +0100
        Re: What practice can get speed improvement in C++? bartekltg <bartekltg@gmail.com> - 2015-07-16 13:23 +0200
          Re: What practice can get speed improvement in C++? Öö Tiib <ootiib@hot.ee> - 2015-07-16 06:54 -0700
            Re: What practice can get speed improvement in C++? bartekltg <bartekltg@gmail.com> - 2015-07-16 17:30 +0200
              Re: What practice can get speed improvement in C++? Öö Tiib <ootiib@hot.ee> - 2015-07-16 11:16 -0700
                Re: What practice can get speed improvement in C++? bartekltg <bartekltg@gmail.com> - 2015-07-17 17:06 +0200
          Re: What practice can get speed improvement in C++? JiiPee <no@notvalid.com> - 2015-08-04 16:14 +0100
  Re: What practice can get speed improvement in C++? Victor Bazarov <v.bazarov@comcast.invalid> - 2015-07-14 20:29 -0400
    Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-07-14 19:50 -0700
  Re: What practice can get speed improvement in C++? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2015-07-15 05:07 +0200
  Re: What practice can get speed improvement in C++? Lőrinczy Zsigmond <nospam@for.me> - 2015-07-15 06:38 +0200
  Re: What practice can get speed improvement in C++? Paavo Helde <myfirstname@osa.pri.ee> - 2015-07-15 00:22 -0500
    Re: What practice can get speed improvement in C++? fl <rxjwg98@gmail.com> - 2015-07-16 04:34 -0700
      Re: What practice can get speed improvement in C++? Martijn van Buul <pino@dohd.org> - 2015-07-21 09:28 +0000
  Re: What practice can get speed improvement in C++? Juha Nieminen <nospam@thanks.invalid> - 2015-08-03 08:16 +0000
    Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-08-03 13:48 -0700
      Re: What practice can get speed improvement in C++? Juha Nieminen <nospam@thanks.invalid> - 2015-08-04 08:21 +0000
        Re: What practice can get speed improvement in C++? Öö Tiib <ootiib@hot.ee> - 2015-08-04 08:07 -0700
        Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-08-04 10:15 -0700
          Re: What practice can get speed improvement in C++? Bo Persson <bop@gmb.dk> - 2015-08-04 20:09 +0200
            Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-08-04 12:38 -0700
              Re: What practice can get speed improvement in C++? Bo Persson <bop@gmb.dk> - 2015-08-05 17:03 +0200
                Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-08-05 23:32 -0700
            Re: What practice can get speed improvement in C++? Öö Tiib <ootiib@hot.ee> - 2015-08-05 03:55 -0700
          Re: What practice can get speed improvement in C++? Christopher Pisz <nospam@notanaddress.com> - 2015-08-04 14:09 -0500
            Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-08-04 12:18 -0700
              Re: What practice can get speed improvement in C++? Christopher Pisz <nospam@notanaddress.com> - 2015-08-04 14:50 -0500
              Re: What practice can get speed improvement in C++? Öö Tiib <ootiib@hot.ee> - 2015-08-05 04:11 -0700
          Re: What practice can get speed improvement in C++? Juha Nieminen <nospam@thanks.invalid> - 2015-08-05 08:12 +0000
            Re: What practice can get speed improvement in C++? Martin Shobe <martin.shobe@yahoo.com> - 2015-08-05 08:53 -0500
            Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-08-05 22:24 -0700
              Re: What practice can get speed improvement in C++? Ian Collins <ian-news@hotmail.com> - 2015-08-06 17:42 +1200
                Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-08-05 22:53 -0700
                Re: What practice can get speed improvement in C++? Öö Tiib <ootiib@hot.ee> - 2015-08-06 00:20 -0700
                Re: What practice can get speed improvement in C++? Christopher Pisz <nospam@notanaddress.com> - 2015-08-06 10:10 -0500
                Re: What practice can get speed improvement in C++? Bo Persson <bop@gmb.dk> - 2015-08-06 17:29 +0200
                Re: What practice can get speed improvement in C++? woodbrian77@gmail.com - 2015-08-06 09:38 -0700
              Re: What practice can get speed improvement in C++? Juha Nieminen <nospam@thanks.invalid> - 2015-08-10 08:25 +0000
  Re: What practice can get speed improvement in C++? pip010 <pip010@gmail.com> - 2015-08-03 04:22 -0700

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