std::vector::reserve + std::vector::push_back in loop is sub-optimal, because push_back needs to check for re-allocation, but that never comes.
std::vector::resize + std::vector::operator[] in loop is also sub-optimal, because resize default-initializes all elements only to be overwritten soon anyway.
This article’s author suggests push_back_unchecked.
I suggest std::vector::insert with pair of random access iterators with custom dereference operator that does the “transform element” or “generate element” functionality. The standard will have resize_and_overwrite hopefully soon.
You are not logged in. However you can subscribe from another Fediverse account, for example Lemmy or Mastodon. To do this, paste the following into the search field of your instance: !programming@programming.dev
Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!
Cross posting is strongly encouraged in the instance. If you feel your post or another person’s post makes sense in another community cross post into it.
Hope you enjoy the instance!
Rules
Rules
Follow the programming.dev instance rules
Keep content related to programming in some way
If you’re posting long videos try to add in some form of tldr for those who don’t want to watch videos
std::vector::reserve + std::vector::push_back in loop is sub-optimal, because push_back needs to check for re-allocation, but that never comes.
std::vector::resize + std::vector::operator[] in loop is also sub-optimal, because resize default-initializes all elements only to be overwritten soon anyway.
This article’s author suggests push_back_unchecked.
I suggest std::vector::insert with pair of random access iterators with custom dereference operator that does the “transform element” or “generate element” functionality. The standard will have resize_and_overwrite hopefully soon.
Moar discussion:
https://codingnest.com/the-little-things-the-missing-performance-in-std-vector/
https://twitter.com/horenmar_ctu/status/1695823724673466532
https://twitter.com/horenmar_ctu/status/1695331079165489161
https://www.reddit.com/r/cpp/comments/162tohr/the_little_things_the_missing_performance_in/
https://www.reddit.com/r/cpp/comments/162tohr/the_little_things_the_missing_performance_in/jy21hgd/
https://twitter.com/basit_ayantunde/status/1644895468399337473
https://twitter.com/MarekKnapek/status/1645272474517422081
https://www.reddit.com/r/cpp/comments/cno9ep/improving_stdvector/