definitions of compiler, standard library, standard template library, etc. (c++)

[khoda]

i'm getting a little confused with some terminology. it's hard to get all of these questions answered through google.

please correct me if i make any mistakes in my assumptions when asking the following questions:

i understand that there are many different compilers for c++. among them is the gnu c++ compiler, part of the gnu compiler collection (gcc). from my understanding, a compiler has a set of rules for syntax and semantics which will allow it to translate c++ code into machine-level code.

first set of questions: who makes these rules for syntax and semantics? i imagine the 'author' of the language has something to do with at the beginning... where/when does the ISO come into play? What exactly is a standard? Is it a list of specs on paper, or an actual deliverable compiler?

some compilers say they come with some libraries for the languages they compile. for example, the gnu c++ compiler comes with libstdc++. what exactly is libstdc++? on their site, they claim it's an ongoing project to implement the standard c++ library. why hasn't this already been implemented? are the people working on this project following the ISO standard (does this imply the ISO standard is a set of rules written on paper?)?

along with different compilers for c++, there are also different implementations of the standard c++ library? what does STL have to do with the standard c++ library? it seems they have some thing in common, and some things not. what are the most compilers/standard librarys today?

[Banfa]

rules for syntax and semantics

This is the standard. Normally what happens is that someone decides to create a language and then if it becomes popular lots of people copy it and put in non-standard features. Then every decides it would be nice if the language was standardised and the ISO get involved and produce a standard for the language. The standard is a document (normally a pdf available on CD or in electronic form) that specifies the language syntax, semantics and behaviour.

For example C++ has the following time line

pre 1983 Bjarne Stroustrup produces C with Classes a C++ precursor
1983 - 1985 Bjarne Stroustrup creates the first C++
1990 ISO organisation gets involved in creating a standard C++
1998 The first ISO C++ stardard is released.

The libraries are part of the standard, the standard defines the function prototypes and what the result of the functions should be. The implementers are free to implement the library in any way they choose as long as they follow what is defined in the standard.

Implementing the standard library is an on-going project because there is a new C++ standard due out soon. Additionally any implementation is free to add extensions.

The STL is the standard C++ library, however also available for C++ programmers is the standard C library although there are very few things in the standard C library that are not in the standard C++ library (the time based functions spring to mind).

[khoda]

Thanks for the reply, Banfa. I'm still a little confused.

I understand that compiler writers can use a plethora of different optimization techniques. It seems that some compilers even have built-in functions (which seems to be distinct from the libraries they offer). Am I right in saying that each of these compilers will take any C++ file (with proper syntax and semantics) and compile it into a a binary file for some machine? Are their different types of compilers for different types of end-users? The GNU C++ compiler seems to be fairly popular, what are the other popular ones?

There also seems to be different attempts to implement the standard C++ library. You mentioned that STL is the standard C++ library. What is libstdc++? Is that a different implementation? Which implementations of the standard c++ library are most popular?

[Banfa]

There are not different compiler implementations for different type of end users.

Any standard conforming C++ compiler will compile any error free standard conforming C++ source file into the object for its target platform.

gcc/g++ is a popular compiler, on the Windows platform Microsoft Visual C++ is also popular.

libstdc++ is GNUs implementation of the C++ standard library. Anyone who produces a C++ compiler is likely to have produced a standard library to accompany their compiler. The only exception to this that I have seen is in the embedded programming world where some embedded platforms do not support all the functions of the standard library, for instance they have no stdin, stdout and stderr or they have no filing system.

Generally people just use the standard library implementation that comes with their compiler.