c++ - Benchmarking linefeed characters vs std::endl -



c++ - Benchmarking linefeed characters vs std::endl -

i'm reading “\n” or '\n' or std::endl std::cout?. despite consensus doesn't matter choose, decided build contrived test measure programme execution speed of each. here simple program:

#include <iostream> int main() { (std::size_t = 0; < iters; ++i) { #ifdef ver1 std::cout << "\n"; #endif #ifdef ver2 std::cout << '\n'; #endif #ifdef ver3 std::cout << std::endl; #endif } }

using 1 billion iterations , -o3 , redirecting output /dev/null/, these results:

class="lang-none prettyprint-override">"\n" 0:30.96 '\n' 0:31.66

with -o2:

class="lang-none prettyprint-override">"\n" 0:32.96 '\n' 0:31.54

why higher optimization level create '\n' slower?

with setup, you're measuring test run happened interrupted longest thread scheduler. also, imagine might different times writing real file instead of /dev/null.

c++

-

Comments

Post a Comment

Popular posts from this blog

formatting - SAS SQL Datepart function returning odd values -

formatting - SAS SQL Datepart function returning odd values - i'm having massive problem project can't seem right. i'm trying modify info variable in datetime format. first info 30mar12:00:00:00. i've been advised utilize code below returns value 30mar60:5:30:00. want date component , have no thought how info got exported in format wasn't in microsoft access. i've tried several mods code 1 time again comes blank or sends error message. proc sql; update dataset set date = datepart(date); quit; any advice appreciated. i'm guessing variable date numeric , formatted datetime. 1 time you've carried out conversion, alter format date9. sas datetime value number of seconds since 01 jan 1960, whereas dates number of days since 01 jan 1960. both stored numbers, using right format display value key. illustration below. data _null_; a='30mar12:00:00:00'dt; b=datepart(a); c=b; format b datetime. c date9.; set b c; run; ...
Read more

c++ - Apple Mach-O Linker Error(Duplicate Symbols For Architecture armv7) -

c++ - Apple Mach-O Linker Error(Duplicate Symbols For Architecture armv7) - here error: duplicate symbol _objc_metaclass_$_bfapplinkreturntorefererview in: /users/user/documents/facebooksdk/facebooksdk.framework/facebooksdk(bfapplinkreturntorefererview.o) /users/user/desktop/project/project/project/assets/facebook/editor/ios/facebooksdk/facebooksdk.a(bfapplinkreturntorefererview.o) ld: 889 duplicate symbols architecture armv7 clang: error: linker command failed exit code 1 (use -v see invocation) i have searched find solution of error couldn't. there tons of similar error this, 1 hasn't been asked yet. problem shows when add together "-objc" "other linker flags". need add together utilize admob service. problem? how can solve this? i faced same issue while integrating facebook-ios-sdk. because using 3rd party library had bolts.framework linked against it. solution found incorporate facebook-ios-sdk source code hosted on github. ...
Read more

php - Yii 2: Unable to find a class into the extension 'yii2-admin' -

php - Yii 2: Unable to find a class into the extension 'yii2-admin' - extension's github project: https://github.com/mdmsoft/yii2-admin i'm using advanced template of yii2, i've backend , frontend , common folders advanced folder. the advanced folder on same level of vendor folder. i've others extensions , working then installed yii2-admin composer php composer.phar require mdmsoft/yii2-admin "*" installation worked well. into vendor folder i've mdmsoft folder yii2-admin subfolder it. this actual content of v endor/yiisoft/extensions.php (modified composer installation, haven't manually touched it) <?php $vendordir = dirname(__dir__); homecoming array ( 'yiisoft/yii2-jui' => array ( 'name' => 'yiisoft/yii2-jui', 'version' => '2.0.0.0', 'alias' => array ( '@yii/jui' => $vendordir . '/yiisoft/yii2-jui', ...
Read more