An informal comparison of the three major implementations of std:string
devblogs.microsoft.com
An informal comparison of the three major implementations of std:string
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Re: An informal comparison of the three major implementations of std:string
#2Obligatory link to a must watch, the CppCon 2016 talk on the complexities of std::string: https://youtu.be/kPR8h4-qZdk?si=x2DbgNIZcKyK5PKt
Re: An informal comparison of the three major implementations of std:string
#3Somewhat related - but there are a ridiculous number of platform/systems that ship with derivative of Dinkum C++ standard library - MSVC (included). When you lookup the company behind it - it's basically small shop that seems to be primarily one guy up in MA.
Re: An informal comparison of the three major implementations of std:string
#4Nice article, thanks for sharing! Been implementing my own string type for fun recently and this is a useful reference!
Re: An informal comparison of the three major implementations of std:string
#5This is great. It would be a good C/C++ interview question to compare these. Of course you can't expect a Raymond Chen level performance, but it should give some insight into experience with low level programming.
Re: An informal comparison of the three major implementations of std:string
#6tl;dr: libc++ is just bad, libstdc++ and MSVC trade punches for first place, with the eyeball win going to the FSF.
Though really the performance gates on string-heavy code tend to be in the heap and not the string library itself.
Re: An informal comparison of the three major implementations of std:string
#7Somewhat related - but there are a ridiculous number of platform/systems that ship with derivative of Dinkum C++ standard library - MSVC (included). When you lookup the company behind it - it's basically small shop that seems to be primarily one guy up in MA.
That one guy has been at it for a very long time. I remember buying Dinkum around 2000.
Re: An informal comparison of the three major implementations of std:string
#8GCC putting a pointer at the top of the structure seems reminiscent of the way Pascal stored strings. A PString is the address of a character buffer like C, but the length of the string is stored at a negative offset. I may be remembering wrong but I think there was an older C++ STL that also used negative offsets.
As much as these snippets make clang look heavier, I wonder what it compiles to in practice when the compiler can make better inferences. If you can prove the state of the `is_small` bit those branches disappear. Even at runtime, which implementation is more performant? Real-world profiling may favor clang with branch prediction and speculative processing. Then again, speculation has become a dirty word lately.[1]
[1] Get it? "Dirty" because of the cache. I'm sorry, that pun was entirely unintentional.
Re: An informal comparison of the three major implementations of std:string
#9The most interesting thing imo is what they all do similarly: they all store the size, instead of the end pointer -- unlike, say, std::vector. Exercise for the reader as to why this is the right tradeoff.
Re: An informal comparison of the three major implementations of std:string
#10Somewhat related - but there are a ridiculous number of platform/systems that ship with derivative of Dinkum C++ standard library - MSVC (included). When you lookup the company behind it - it's basically small shop that seems to be primarily one guy up in MA.
This one guy has something like badge #10 in C++