When I install an IDE like VB for example, it has C++ libraries.
The question is, how to know the contents of a library (methods or manipulators) the way I am intended to do.
Where should a beginner find the contents formally? I found them in Wikipedia, but I want to know the original source (if we suppose that no internet connection is available).
MSDN would be a good source. And C++ Reference too.
You can donwload the current image of cppreference.com wiki at this address. It is updated daily.
Simple question here, when i install an IDE like vb for example, it has c++ libraries.
What libraries are you referring to?
where should a beginner find the contents formally?
Libraries that are meant for public consumption are described in their respective documentation. Where that documentation is found differs greatly. Most documentations for big public libraries are found online, on the official websites of these libraries, though.
Since the question explicitly mentioned C++, the C++ standard libraries are described at cplusplus.com. There is another large collection of C++ libraries, called Boost which is described on their homepage.
The libraries that ship with VB (which VB, though? VB.NET or VB6?) are Microsoft’s, and are therefore described on their developer network homepage, msdn.microsoft.com. An offline copy of this documentation is installed with Visual Studio; however, the software used to navigate it is barely usable (especially when accessed via Visual Studio).
The original source are the header files (.h files). In these files you will find the functions declarations and class definitions. In some cases, like template code, you will also see the implementationl. In others, the implementation will be precompiled into a .dll or .lib file and you can't see it. But all available things are in the header file. To use its contents you must #include the header file and link against the implementation. For standard library, the linking is done for you by the IDE
Everything that comes with Visual Studio and its subset installations is documented on MSDN. Do you have more specific questions re the C++ libraries? Do you need info on Win32, C runtime (CRT), C++ standard library?
Every lib usually has a coupled header (.h) file that describes the signatures of methods and types available with that library. The library is linked (or dynamically loaded and linked) with the executable while the header is used during compilation to the purpose of static checking the source.
You should just look for an include folder and check its contents.
The contents of a library is contained in the headers which ship with your IDE.
The .h files contain just the function declarations. The source containing the definitions is already compiled, so when you include a header, the linker looks for the function definitions in the libraries that you have linked. Most of the libraries are open source, some of them are just specifications that anyone can implement for example OpenGL, and the standard library is a specification, too. The same goes for the C++ language. Then programmers use the specifications to write implementations (GCC, VC++).
Here you can download the source code of STL C++ https://www.sgi.com/tech/stl/download.html
Related
I am learning C++ and, in order to do so, am writing a sample wxWidgets application.
However, none of the documentation I can find on the wxWidgets website tell me what library names to pass to the linker.
Now, apart from wxWidgets, is there a general rule of thumb or some other convention by which I should/would know, for any library, what the names of the object files are against which I am linking?
We have more of a "rule of ring finger", instead of a thumb
Generally, if you compile the library by hand, it will produce several library files (usually .a .lib or something similar, depending entirely on your compiler and your ./configure) these are produced (typically) because of a makefile's build script.
Now a makefile can be edited in any way the developer pleases, but there are some good conventions (there is, in fact, a standard) many follow- and there are tools to auto generate the make files for the library (see automake)
Makefiles are usually consistent
You can simply use the makefile to generate the files, and if it's compliant, the files will be placed in a particular folder (the lib folder I believe?) all queued up and ready to use!
Keep in mind, a library file is simply the implementation of your code in precompiled format, you could create a library yourself from your code quite easily using the ar tool. Because it is code, just like any other code, you don't necessarily want to include all of the library files for a given library. For instance with wxWidgets if you're not using rich text, you certainly don't want to waste the extra space in your end executable by including that library file. Later if you want to use it, you can add it to your project (just like adding a .cpp file)
Oh and also with wxWidgets, in their (fantastic) documentation, each module will say what header you need to include, and what library it is a part of.
Happiness
Libraries are amazing, magical, unicorns of happiness. Just try not to get too frustrated with them and they'll prance in the field of your imagination for the rest of your programming career!
After a bit more Googling, I found a page on the wxWidgets wiki which relates to the Code::Blocks IDE, but which also works for me. By adding the following to the linker options, it picks up all the necessary files to link:
`wx-config --libs`
(So that does not solve my "general rule" problem; for any library I am working with, I still have to find out what files to link against, but at least this solves the problem for wxWidgets).
The build instructions are different for each platform and so you need to refer to the platform-specific files such as docs/gtk/install.txt (which mentions wx-config) or docs/msw/install.txt to find them.
FWIW wxWidgets project would also definitely gratefully accept any patches to the main manual improving the organization of the docs.
A bit of a simple question, though the answer may not be. I am fairly new to C++ and was wondering if it was possible to open a C++ library and see it's code. It sounds like a potentially risky move to accidentally change the core code of the library, but I would still like to see if it is possible. Thank you!
There are too kinds of libraries that C++ can use:
compiled to binary libraries which are linked with linker to your
executable;
headers-only libraries which are just included with include into
your source code
You can "open" headers of headers-only libraries and modify code if you wish (but not recommended).
Also many compiled libraries are open source. You can open source files there. If you want to modify such library, you will need to compile it and link your executable against this modified version.
Yes it s possible to open a c++ library and see its code.
If you want to make changes to any functionality simply create your own version of it giving it a different name, or if you want to add functionality just simply extend the class you are interested in. (read up on inheritance for this).
On Linux (Ubuntu) what is the path and file name where I can see the C/C++ code used in the malloc() and new() implementations?
I have looked in /usr/include but started to lose my way around. Does it depend on which version of gcc/g++ I have installed?
If someone could also give a general answer which would help me understand how Linux stores all the "native" functions it would be most appreciated and I wouldnt ever have to ask again for a different function.
One thing: new is a C++ keyword that uses malloc.
The source for malloc is in the source for your version of libc, which is probably glibc. Look at their source.
Other built in functions that are system calls only have shell implementations in glibc that call the underlying syscall.
The GIT of the GNU standard C lib implementation can be found here.
From this point in the tree you should be able to find the rest as well.
The "implementation" is a library you can link (an "a" file or an "so" file) plus an header that contains the declaration (an "h" file).
The C and CPP files sits on the computer that created those libraries before they had been used to build-up your system. And since their source is not required for your programs to work (you just link the binaries, not the sources) they are not distributed together with the system build.
That's why you have to download those files from the source repositories, jut like if you want yourself to rebuild the system.
You find this in the implementation of the C Standard Library the compiler uses.
I'm not sure for Ubunta. Debian's gcc uses eglibc, which's sources could be found here.
When I compile a program with #include
where can I see the contents of that file, and also since that file contains declarations, where can I see the actual code used in those functions?
Is it open to everyone or is it not available to the public?
The actual code is in the platform-specific standard libraries that come with your compiler, you can see it by looking at the standard library implementation source.
Here's the documentation (and source) for libstdc++ by GNU (it comes with gcc): http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/index.html.
Download the source from one of these mirrors: http://gcc.gnu.org/mirrors.html
Generally the #included file is readable, but the library it implements is generally not readable. The include files on a mac are in /usr/include/c++.
The library code depends on the compiler. For Gnu C++ used in linux and Mac you can definitely see the code. You might have to download it. It is available at http://gcc.gnu.org/libstdc++/
I don't think Windows C++ library code is available.
It depends on what toolchain you are using, not every vendor is making his implementation public. You can have a look at the GNU C library for starters: http://www.gnu.org/software/libc/
Dinkumware, the company behind the C++ standard template library that is used in Visual Studio for example, is offering a commercial product, thus the code is not available to everyone - it really depends on your license. Some versions of Visual Studio indeed ship with the source code of the runtime included.
As for the STL, there is also STLport, an open source STL implementation.
Your best bet will indeed be the projects that gcc/g++ depend on.
The C++ standard itself is just this: a standard. The implementation of which is done by many vendors. STLport and GNU libstdc++ are both open source and can be looked at as a whole. Visual Studio ships with Dinkumware C++ standard library. It is closed source.
Nevertheless, you can always see the source of the headers by opening the include directory of your C++ standard lib. The files are named just like you include them. Much of it is implemented in headers anyway. But are pretty much unreadable to the untrained eye.
But when it comes to using the C++ library don't depend on the exact source code of it, but rather on what the C++ standard says. Don't program to an implementation, but rather to the standard.
Run this command from your command line:
find /usr -name iostream
That will tell you the directory you want.
If you use something like Visual Studio, you can put a break point and then start line-by-line stepping through your code and it will open the included files as you go along. Quickest way into a file in my opinion. Otherwise you can find the code somewhere on your PC ... on mine its in C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\crt\src\ostream for example, replacing ostream with iostream, sstream, etc (note that those are file names without extensions) but also if you look at the directory you'll see a lot of .h and .c files
All system headers ship with your compiler. On Linux systems, these can normally be found under /usr/include . On other platforms, the will normally live where you installed the compiler.
Commercial libraries do not normally ship source code. On linux, these can normally be found in the source pacakges.
similar to iostream.h ,conio.h , ...
The standard library is generally all templates. You can just open up the desired header and see how it's implemented†. Note it's not <iostream.h>, it's <iostream>; the C++ standard library does not have .h extensions. C libraries like <string.h> can be included as <cstring> (though that generally just includes string.h)
That said, the run-time library (stuff like the C library, not-template-stuff) is compiled. You can search around your compiler install directory to find the source-code to the run-time library.
Why? If just to look, there you go. But it's a terrible way to try to learn, as the code may have non-standard extensions specific to the compiler, and most implementations are just generally ugly to read.
If you have a specific question about the inner-workings of a function, feel free to start a new question and ask how it works.
† I should mention that you may, on the off chance, have a compiler that supports export. This would mean it's entirely possible they have templated code also compiled; this is highly unlikely though. Just should be mentioned for completeness.
From a comment you added, it looks like you're looking for the source to the implementations of functions that aren't templates (or aren't in the header file for whatever reason). The more traditional runtime library support is typically separately compiled and in a library file that gets linked in to your program.
The majority of compilers provide the source code for the library (though it's not guaranteed to be available), but the source files might be installed anywhere on your system.
For the Microsoft compilers I have installed, I can find the source for the runtime in a directory under the Visual Studio installed location named something like:
vc\crt\src // VS2008
vc7\crt\src // VS2003
vc98\crt\src // VC6
If you're using some other compiler, poke around the installation directory (and make sure that you had asked that runtime sources to be installed when you installed your compiler tools).
As mentioned, it is implementation specific but there is an easy way to view contents of header files.
Compile your code with just preprocessing enabled for gcc and g++ it is -E option.
This replaces the contents of header files by their actual content and you can see them.
On linux, you can find some of them in /usr/include
These files merely contain declarations and macro definitions.The actual implementation source files can be obtained from the library provider e.g the source code of standard C++ Library(libstdc++) is obtainable here.
According to the C++ language specification, implementors do not have to put standard headers into physical files. Implementors are allowed to have the headers hard coded in the translator's executable.
Thus, you may not be able to view the contents of standard header files.