My original plan was it to write about the rules of the C++ Core Guidelines to the regex and chrono library, but besides the subsection title, there is no content available. I already wrote a few posts about time functionality. So I'm done. Today, I fill the gap and write about the regex library.

As easy as my title and the rules of the C++ core guidelines sound, getting more performance out of the Iostreams is no no-brainer.

Today's post is about what you should know about Iostreams. In particular, I write about formatted and unformatted In- and Output.

When you interact with the outside world, the iostream library is the way to go in C++. As always you have to keep a few rules in mind. Let me show, which rules.

The C++ core guidelines use the term string as a sequence of characters. Consequently, the guidelines are about  C-strings, C++-strings, the C++17 std::string_view's, and std::byte's. 

When you access an element outside a container of the STL, the result is not so promising. You effect may be an error or undefined behaviour. Undefined behaviour means all bets are open.

Modern C++ has eight associative containers, but your special friends should be std::map and std::unordered_map. Why? Let me explain it in this post.

In 99 % of your use-cases for a sequential container, you are totally fine with a std::array or a std::vector. What? If you don't believe me, read this post.

The rules to the C++ standard library are mainly about containers, strings, and iostreams.

 My last post gave you the introduction to modules in C++20. This post shows, how to use existing modules.