Related
Starting in C++11 (I think) a lot of Boost functionality was available in the STL, or in an extension TR1 (again, if memory serves).
I'm struggling to tell specifically which things were and were not included in C++11 and later versions (and in MSVC++ versions).
Specifically this very old question about joining vector<string> has a nice Boost-based answer: https://stackoverflow.com/a/6334153/197229.
I don't want to add boost dependency to my project so - is this functionality now available in standard libraries?
boost::algorithm::join is not part of the C++ standard library. (nor something with equivalent functionality).
More generally, sometimes things are implemented in Boost.Algorithm and then proposed for standardization (Boyer-Moore, for example), and sometimes I implement things that have been added to the standard library in Boost.Algorithm for people who can't/won't use the latest C++ version (any_of, for example).
boost::algorithm::join has not made its way into the standard library as of yet. There is an open paper (N3594) to have it added to the library, but it is sitting in the Library Evolution working group currently.
You'll either need to use one of the other implementations from that Q&A pair or include boost.
Someone brought this article to my attention that claims (I'm paraphrasing) the STL term is misused to refer to the entire C++ Standard Library instead of the parts that were taken from SGI STL.
(...) it refers to the "STL", despite the fact that very few people still use the STL (which was designed at SGI).
Parts of the C++ Standard Library were based on parts of the STL, and it is these parts that many people (including several authors and the notoriously error-ridden cplusplus.com) still refer to as "the STL". However, this is inaccurate; indeed, the C++ standard never mentions "STL", and there are content differences between the two.
(...) "STL" is rarely used to refer to the bits of the stdlib that happen to be based on the SGI STL. People think it's the entire standard library. It gets put on CVs. And it is misleading.
I hardly know anything about C++'s history so I can't judge the article's correctness. Should I refrain from using the term STL? Or is this an isolated opinion?
The "STL" was written by Alexander Stepanov in the days long before C++ was standardised. C++ existed through the 80s, but what we now call "C++" is the language standardised in ISO/IEC 14882:2014 (and earlier versions, such as ISO/IEC 14882:2011).
The STL was already widely used as a library for C++, giving programmers access to containers, iterators and algorithms. When the standardisation happened, the language committee designed parts of the C++ Standard Library (which is part of the language standard) to very closely match the STL.
Over the years, many people — including prominent book authors, and various websites — have continued to refer to the C++ Standard Library as "the STL", despite the fact that the two entities are separate and that there are some differences. These differences are even more pronounced in the upcoming new C++ standard, which includes various features and significantly alters some classes.
The original STL is now often called "an implementation of the C++ Standard Template Library" (rather backwards to actual history!), in the same way that your Microsoft Visual Studio or GCC ships an implementation of the C++ Standard Library. But the "Standard Template Library" and the "Standard Library" are not the same thing.
The battle is about whether the current Standard Library should be called "the STL" in whole or in part, and/or whether it matters what it's called.
For "STL"
There is a school of thought that says that everybody knows now that "STL" means the standard library, just as everybody now knows that "C++" is the ISO-standardised language.
It also includes those who believe that it doesn't really matter as long as all parties understand what is being talked about.
It's a term made even more prevalent by the nature of the beast, much of which makes heavy use of the C++ feature known as "templates".
For "C++ Standard Library" (or stdlib)
However, there is another school of thought — to which I subscribe — that says that this is confusing. People learning C++ for the first time do not know this distinction, and may not notice small language differences.
The author of that article has numerous times encountered people who believe that the entire C++ Standard Library is the STL, including features that were never part of the STL itself. Most vocal proponents of "the STL", in contrast, know exactly what they mean by it and refuse to believe that not everybody "gets it". Clearly, the term's usage is not uniform.
In addition, there are some STL-like libraries that are in fact implementations of the original STL, not the C++ Standard Library. Until recently, STLPort was one of them (and even there, the confusion abounds!).
Further, the C++ Standard does not contain the text "STL" anywhere, and some people habitually employ phrases like "the STL is included in the C++ Standard Library", which is plain incorrect.
It's my belief that continuing to propagate the usage of the term in this way will just lead to the misunderstanding going on forever. Alas, it may be entirely counter-productive to attempt to change things, even if it's supposed to be for the better. We may just be stuck with double-meanings forever.
Conclusion
I appreciate that this post has been a little biased: I wrote the article you linked to. :) Anyway, I hope this helps to explain the battle a bit better.
Update 13/04/2011
Here are three perfect examples of someone who is using "the STL" to refer to the entire C++ Standard Library. It continues to baffle me that so many people swear blind that nobody ever does this, when it's plain to see almost on a daily basis.
There is no one answer that's really correct. Alexander Stepanov developed a library he called STL (working for HP at the time). That library was then proposed for inclusion in the C++ standard.
That basically "forked" development. The committee included some parts, rejected others completely, and redesigned a few (with Alexander's participation). Development of the original library was later moved to Silicon Graphics, but continued separately from the C++ standard library.
After those pieces were added to the standard library, some other parts of the standard library were modified to fit better with what was added (e.g., begin, end, rbegin and rend were added to std::string so it could be used like a container). Around the same time, most of the library (even pieces that were completely unrelated) were made into templates to accommodate different types (e.g., standard streams).
Some people also use STL as just a short form of "STandard Library".
That means when somebody uses the term "STL" they could be referring to any of about half a dozen different things. For better or worse, most people who use it seem to ignore the multiplicity of meanings, and assume that everybody else will recognize what they're referring to. This leads to many misunderstandings, and at least a few serious flame-wars that made most of the participants look foolish because they were simply talking about entirely different things.
Unfortunately, the confusion is likely to continue unabated. It's much more convenient to refer to "STL" than something like "the containers, iterators, and algorithms in the C++ standard library, but not including std::string, even though it can act like a container." Even though "C++ standard library" isn't quite as long and clumsy as that, "STL" is still a lot shorter and simpler still. Until or unless somebody invents terms that are more precise (when necessary), and just as convenient, "STL" will continue to be used and confusion will continue to result.
The term "STL" or "Standard Template Library" does not show up anywhere in the ISO 14882 C++ standard. So referring to the C++ standard library as STL is wrong. The term "C++ Standard Library" or "standard library" is what's officially used by ISO 14882:
ISO 14882 C++ Standard:
17 - Library introduction [lib.library]:
This clauses describes the contents of the C++ Standard Library, how
a well-formed C++ program makes use of
the library, and how a conforming
implementation may provide the
entities in the library.
...
STL is a library originally designed by Alexander Stepanov, independent of the C++ standard. However, some components of the C++ standard library include STL components like vector, list and algorithms like copy and swap.
But of course the C++ standard includes much more things outside the STL, so the term "C++ standard library" is more correct (and is what's actually used by the standards documents).
I've made this same argument recently, but I believe a little tolerance can be allowed. If Scott Meyers makes the same mistake, you're in good company.
From the GNU Standard C++ Library (libstdc++) FAQ:
The STL (Standard Template Library) was the inspiration for large chunks of the C++ Standard Library, but the terms are not interchangeable and they don't mean the same thing. The C++ Standard Library includes lots of things that didn't come from the STL, and some of them aren't even templates, such as std::locale and std::thread.
Libstdc++-v3 incorporates a lot of code from the SGI STL (the final merge was from release
3.3). The code in libstdc++ contains many fixes and changes compared to the original SGI code.
In particular, string is not from SGI and makes no use of their "rope" class (although that is included as an optional extension), neither is valarray nor some others. Classes like vector<> were from SGI, but have been extensively modified.
More information on the evolution of libstdc++ can be found at the API evolution and backwards compatibility documentation.
The FAQ for SGI's STL is still recommended reading.
FYI, as of March 2018 even the official STL web site www.sgi.com/tech/stl/ is gone.
In layman words: STL is part of Standard Library.
C++ Standard Library is group into:
Standard Functional Library
-I/O,
-String and character handling,
-Mathematical,
-Time, date, and localization,
-Dynamic allocation,
-Miscellaneous,
-Wide-character functions
Standard OOP and Generics Library
-The Standard C++ I/O Classes
-The String Class
-The Numeric Classes
-The STL Container Classes
-The STL Algorithms
-The STL Function Objects
-The STL Iterators
-The STL Allocators
-The Localization library
-Exception Handling Classes
-Miscellaneous Support Library
So if you are talking about STL as Standard Library, it is OK and just remember that STL implementations allow for generics and others are more specific to one type.
Please refer to https://www.tutorialspoint.com/cplusplus/cpp_standard_library.htm
C++ Standard Library includes C++ STL
The contents of the C++ standard library are:
C++ version of C language header file
C++ IO header file
C++ STL
So please don’t confuse the C++ standard library with STL.
I'm confused about some of the documentation at cplusplus.com. Have I used the standard template library with either of these two lines of code?
for (std::string::const_iterator it = str.begin(); l < data.size; ++it, ++l)
and
tile_tag(): distance(std::numeric_limits<int>::max()), dir(unknown_direction), used(false)
See:
http://www.cplusplus.com/reference/string/string/begin/
and
http://www.cplusplus.com/reference/std/limits/numeric_limits/
If I have used STL, how can I modify them to do what they do without STL?
Thanks!
EDIT: I guess this is OUR definition of STL: http://www.sgi.com/tech/stl/stl_index_cat.html
I don't see const_iterator...but I do see max. But is that the max I used?
Yes, you used it, since std::string alone is "part of the STL", but, more importantly, you are using the iterators, which are a distinctive trait of the STL.
Now, for the mandatory purists part: the STL was a library published by SGI and developed mainly by Alexander Stepanov. What I think you are referring to is "the part of the SGI STL which was later included into the standard with some minor modifications", i.e. all the generic containers/algorithms/iterators stuff.
The usage of the term "STL" for this stuff is tolerated, what is plain wrong, instead, is calling "STL" the whole C++ standard library (which includes a lot of other stuff, e.g. iostreams, locale, the library inherited from C, ...).
If I have used STL, how can I modify them to do what they do without STL?
Why would you want to do that? Anyhow, you have several options, that span from rewriting such classes and algorithms from scratch to using simpler data structures (e.g. C strings) reimplementing only the algorithms you need. Anyway, they both imply reinventing the wheel (and probably reinventing a square wheel), so I'd advise you against doing this unless you have a compelling reason.
EDIT: I guess this is OUR definition of STL: http://www.sgi.com/tech/stl/stl_index_cat.html
Are you sure? Almost no one today uses the SGI STL, generally you use the (more or less) equivalent portion of your C++ standard library (that, by the way, is what you are doing in your code, since you are getting everything from the std namespace).
I don't see const_iterator...
const_iterator is a typedef member of basic_string<char>, you find it in its page.
but I do see max. But is that the max I used?
No, it's not it, your max is not a global function, but a member of the std::numeric_limits template class. Such class do not come from the STL.
Does your code include the namespace std? Then yes, you have used the Standard library. How you can you modify your code to not use the Standard library? Why on earth would you want to? Implementations must provide it- that's why it's called Standard. But if you're truly insane and feel the need to not use it, then ... look up the documentation on what those functions and classes do and write your own replacement.
You have used the STL std::string and std::numeric_limits. I don't know why you would want to avoid using STL (perhaps homework?). You could use old style C strings with a char* and the macro definition MAX_INT from C limits.
What is this "STL" you speak of?
There was this thing that SGI developed in the mid 90s. Yeah, that's 15+ years ago. Older than the previous C++ standard. Back in the days when compilers like Turbo C++ and Borland C++ were best-of-breed; when people used the phrase "C with classes" unironically and without derision; when the idea of compiling C++ primarily by first cross-compiling to C was finally being abandoned; when exceptions were (at least in this context!) a new idea.
They called it "STL" for "standard template library", and they were doing a bunch of neat things with templates and developing new idioms. For its time, it was pretty revolutionary. So much so, in fact, that almost all of its stuff got officially accepted into the standard library with the 1999 standardization of the language. (Similarly, lots of Boost stuff - although nowhere near all; Boost is huge - has been added to the std namespace in the new standard.)
And that's where it died.
Unless you are specifically referring to a few oddball things like std::iota or lexicographical_compare_3way, it is not appropriate to speak of "the STL", and it hasn't been appropriate to speak of "the STL" for twelve years. That's an eternity in computer science terms. (But, hell, I still seem to keep hearing about new installations of Visual C++ 6.0, and some people using even older compilers...)
You're using the standard library of the C++ language. I guess you could write "SC++L" if you like, but that's a bit awkward, isn't it? I mean, no sane Java programmer would ever refer to the SJL, nor any Pythonista to the SPL. Why would you need jargon to talk about using the standard library of the language you are using?
This is what you're supposed to do by default, after all. Could you imagine writing code in C without malloc, strlen et. al.? Avoiding std::string in C++ would be just as silly. Sure, maybe you want to use C++ as a systems programming language. But really, the kinds of applications where you absolutely have to squeeze out every cycle (keep in mind that using std::string is often more efficient than naive string algorithms, and difficult to beat with hard work, because of the simple algorithmic benefits of caching the string length count and possibly over-allocating memory or keeping a cache for short strings) are generally not ones that involve string processing.
(Take it from me - I have several years' experience as a professional mobile game developer, dating to when phones were much, much less powerful: the standard approach to string processing is to redesign everything to need as little of it as possible. And even when you do have to assemble - and line-wrap - text, it was usually not worth optimizing anyway because the time the code spends on that is dwarfed by the time it takes to actually blit the characters to screen.)
"STL" can mean a number of things.
Formally, the name "STL" was only ever used for the library developed by Stepanov, and which is now hosted by SGI. The library consisted, roughly speaking, of containers (vector, list, deque, map, set and all those), iterators and algorithms (and a few other bits and pieces, such as allocators)
This library was adopted and adapted into the C++ standard library when the language was standardized in 1998. In this process, a number of changes were made: corners were cut, components were left out, in order to keep the library small, and to make it easy to swallow for the committee members. A number of changes in order for it to better interoperate with the rest of the standard library, or with the language itself, and certain parts of the existing standard library were modified to become a bit more STL-like.
Today, it's really not very useful to discuss the original STL. So when most C++ developers say "STL", they mean "the part of the C++ standard library that was created when the STL was adopted into the standard". In other words, all the container classes, the iterators and the algorithms in the standard library, are commonly called "STL", simply because they look a lot like the "original" STL, and they're a lot more relevant today than the original library.
But this also means that the term has become rather fluffy and vague. The std::string class was not a part of the original STL. But it was modifed to behave "STL-like". For example, it was given iterators, so that it can be used with the STL algorithms. Should it be considered a part of the STL? Maybe, maybe not.
And to forther confuse matters, the STL became fashionable after it was adopted into the language. Suddenly, people started talking about "STL-style". The Boost libraries, for example, are generally written in a very STL-like way, and some Boost libs have been adopted into the standard library in C++11. So should they now be considered part of the STL?
Probably not, but you could make a pretty good case that they should: that they follow the spirit of the STL, and if Stepanov had thought of them when he write the original STL library, maybe he'd have included them.
Except for a few purists, who think that everyone is better off if the term "STL" is used exclusively to refer to something that no one ever actually needs to refer to (the SGI library), and if we have no way to refer to the standard library subset that it spawned, pretty much any C++ developer can agree that if you've used the standard library containers OR the standard library iterators OR the standard library algorithms, then you have used the STL.
In your code I see an iterator. So yes, you've used at least a small corner of the STL.
But why does it matter?
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Closed 11 years ago.
Possible Duplicate:
What's this STL vs. “C++ Standard Library” fight all about?
I am very much used to the term STL ("Standard Template Library") and I catch myself often using it when I really mean the C++ Standard Library. So, since almost everything in the C++(-11) Standard Library is a template nowadays, I wonder: Is there a definition what is STL and what is not, in the C++Standard-Lib? Maybe containers, streams, algorithms, etc?
Or should I just stop using the term "STL", because it's the historic one that SGI (correct?) used for their lib years back? It will be difficult...
STL has evolved into C++ Standard Library, it contained containers, iterators and algorithms but not streams. It is better not to use term "STL" it is the name of the old library.
Someone brought this article to my attention that claims (I'm paraphrasing) the STL term is misused to refer to the entire C++ Standard Library instead of the parts that were taken from SGI STL.
(...) it refers to the "STL", despite the fact that very few people still use the STL (which was designed at SGI).
Parts of the C++ Standard Library were based on parts of the STL, and it is these parts that many people (including several authors and the notoriously error-ridden cplusplus.com) still refer to as "the STL". However, this is inaccurate; indeed, the C++ standard never mentions "STL", and there are content differences between the two.
(...) "STL" is rarely used to refer to the bits of the stdlib that happen to be based on the SGI STL. People think it's the entire standard library. It gets put on CVs. And it is misleading.
I hardly know anything about C++'s history so I can't judge the article's correctness. Should I refrain from using the term STL? Or is this an isolated opinion?
The "STL" was written by Alexander Stepanov in the days long before C++ was standardised. C++ existed through the 80s, but what we now call "C++" is the language standardised in ISO/IEC 14882:2014 (and earlier versions, such as ISO/IEC 14882:2011).
The STL was already widely used as a library for C++, giving programmers access to containers, iterators and algorithms. When the standardisation happened, the language committee designed parts of the C++ Standard Library (which is part of the language standard) to very closely match the STL.
Over the years, many people — including prominent book authors, and various websites — have continued to refer to the C++ Standard Library as "the STL", despite the fact that the two entities are separate and that there are some differences. These differences are even more pronounced in the upcoming new C++ standard, which includes various features and significantly alters some classes.
The original STL is now often called "an implementation of the C++ Standard Template Library" (rather backwards to actual history!), in the same way that your Microsoft Visual Studio or GCC ships an implementation of the C++ Standard Library. But the "Standard Template Library" and the "Standard Library" are not the same thing.
The battle is about whether the current Standard Library should be called "the STL" in whole or in part, and/or whether it matters what it's called.
For "STL"
There is a school of thought that says that everybody knows now that "STL" means the standard library, just as everybody now knows that "C++" is the ISO-standardised language.
It also includes those who believe that it doesn't really matter as long as all parties understand what is being talked about.
It's a term made even more prevalent by the nature of the beast, much of which makes heavy use of the C++ feature known as "templates".
For "C++ Standard Library" (or stdlib)
However, there is another school of thought — to which I subscribe — that says that this is confusing. People learning C++ for the first time do not know this distinction, and may not notice small language differences.
The author of that article has numerous times encountered people who believe that the entire C++ Standard Library is the STL, including features that were never part of the STL itself. Most vocal proponents of "the STL", in contrast, know exactly what they mean by it and refuse to believe that not everybody "gets it". Clearly, the term's usage is not uniform.
In addition, there are some STL-like libraries that are in fact implementations of the original STL, not the C++ Standard Library. Until recently, STLPort was one of them (and even there, the confusion abounds!).
Further, the C++ Standard does not contain the text "STL" anywhere, and some people habitually employ phrases like "the STL is included in the C++ Standard Library", which is plain incorrect.
It's my belief that continuing to propagate the usage of the term in this way will just lead to the misunderstanding going on forever. Alas, it may be entirely counter-productive to attempt to change things, even if it's supposed to be for the better. We may just be stuck with double-meanings forever.
Conclusion
I appreciate that this post has been a little biased: I wrote the article you linked to. :) Anyway, I hope this helps to explain the battle a bit better.
Update 13/04/2011
Here are three perfect examples of someone who is using "the STL" to refer to the entire C++ Standard Library. It continues to baffle me that so many people swear blind that nobody ever does this, when it's plain to see almost on a daily basis.
There is no one answer that's really correct. Alexander Stepanov developed a library he called STL (working for HP at the time). That library was then proposed for inclusion in the C++ standard.
That basically "forked" development. The committee included some parts, rejected others completely, and redesigned a few (with Alexander's participation). Development of the original library was later moved to Silicon Graphics, but continued separately from the C++ standard library.
After those pieces were added to the standard library, some other parts of the standard library were modified to fit better with what was added (e.g., begin, end, rbegin and rend were added to std::string so it could be used like a container). Around the same time, most of the library (even pieces that were completely unrelated) were made into templates to accommodate different types (e.g., standard streams).
Some people also use STL as just a short form of "STandard Library".
That means when somebody uses the term "STL" they could be referring to any of about half a dozen different things. For better or worse, most people who use it seem to ignore the multiplicity of meanings, and assume that everybody else will recognize what they're referring to. This leads to many misunderstandings, and at least a few serious flame-wars that made most of the participants look foolish because they were simply talking about entirely different things.
Unfortunately, the confusion is likely to continue unabated. It's much more convenient to refer to "STL" than something like "the containers, iterators, and algorithms in the C++ standard library, but not including std::string, even though it can act like a container." Even though "C++ standard library" isn't quite as long and clumsy as that, "STL" is still a lot shorter and simpler still. Until or unless somebody invents terms that are more precise (when necessary), and just as convenient, "STL" will continue to be used and confusion will continue to result.
The term "STL" or "Standard Template Library" does not show up anywhere in the ISO 14882 C++ standard. So referring to the C++ standard library as STL is wrong. The term "C++ Standard Library" or "standard library" is what's officially used by ISO 14882:
ISO 14882 C++ Standard:
17 - Library introduction [lib.library]:
This clauses describes the contents of the C++ Standard Library, how
a well-formed C++ program makes use of
the library, and how a conforming
implementation may provide the
entities in the library.
...
STL is a library originally designed by Alexander Stepanov, independent of the C++ standard. However, some components of the C++ standard library include STL components like vector, list and algorithms like copy and swap.
But of course the C++ standard includes much more things outside the STL, so the term "C++ standard library" is more correct (and is what's actually used by the standards documents).
I've made this same argument recently, but I believe a little tolerance can be allowed. If Scott Meyers makes the same mistake, you're in good company.
From the GNU Standard C++ Library (libstdc++) FAQ:
The STL (Standard Template Library) was the inspiration for large chunks of the C++ Standard Library, but the terms are not interchangeable and they don't mean the same thing. The C++ Standard Library includes lots of things that didn't come from the STL, and some of them aren't even templates, such as std::locale and std::thread.
Libstdc++-v3 incorporates a lot of code from the SGI STL (the final merge was from release
3.3). The code in libstdc++ contains many fixes and changes compared to the original SGI code.
In particular, string is not from SGI and makes no use of their "rope" class (although that is included as an optional extension), neither is valarray nor some others. Classes like vector<> were from SGI, but have been extensively modified.
More information on the evolution of libstdc++ can be found at the API evolution and backwards compatibility documentation.
The FAQ for SGI's STL is still recommended reading.
FYI, as of March 2018 even the official STL web site www.sgi.com/tech/stl/ is gone.
In layman words: STL is part of Standard Library.
C++ Standard Library is group into:
Standard Functional Library
-I/O,
-String and character handling,
-Mathematical,
-Time, date, and localization,
-Dynamic allocation,
-Miscellaneous,
-Wide-character functions
Standard OOP and Generics Library
-The Standard C++ I/O Classes
-The String Class
-The Numeric Classes
-The STL Container Classes
-The STL Algorithms
-The STL Function Objects
-The STL Iterators
-The STL Allocators
-The Localization library
-Exception Handling Classes
-Miscellaneous Support Library
So if you are talking about STL as Standard Library, it is OK and just remember that STL implementations allow for generics and others are more specific to one type.
Please refer to https://www.tutorialspoint.com/cplusplus/cpp_standard_library.htm
C++ Standard Library includes C++ STL
The contents of the C++ standard library are:
C++ version of C language header file
C++ IO header file
C++ STL
So please don’t confuse the C++ standard library with STL.