If I'm compiling a C program with gcc, I can safely assume that the functions in regex.h are available. Is there a regex library I can assume is there if someone is compiling with microsoft's C compiler?
C++ only, but may be something you can use (or wrap):
Visual C++ 2010 includes the TR1 regex library support.
http://msdn.microsoft.com/en-us/library/bb982382.aspx
It's also available for VC++ 2008 in a feature pack:
http://www.microsoft.com/downloads/details.aspx?FamilyId=D466226B-8DAB-445F-A7B4-448B326C48E7&displaylang=en
No, I don't think MSVC comes bundled with any regex library.
Regex isn't part of the C/C++ standard library, so you shouldn't rely on any compiler providing such a library by default. It's best to get hold of a separate regex library for C (I'm sure there are tons available) and include it with your code.
Try Boost or wait for release of C++1x...
There's no C/C++ regexp library bundled with msvc. C++/CLI have access to the .NET regexp classes though.
Perhaps you can use PCRE
If you want POSIX-compatible regular expression semantics (and the same API too!) then the best regex library is TRE: http://laurikari.net/tre/
Unlike most regex implementations, it follows POSIX exactly in regards to the matches it returns for parenthesized subexpressions, and it's O(n) whereas most implementations are O(2^n) in time.
Google also has a new regex implementation that uses Perl-compatible syntax if you prefer that. You can find a link on the TRE website.
Edit: By the way, TRE seems to come with project files to build it under MSVC.
Related
Let assume a complex project (in C/C++), is there a solution to know which sources files are responsible/used for the creation of a specific binary without compiling the project itself.
I know I could just read the Makefile and try to follow the dependency chain like this but it's not very scalable and it could be hard if multiple Makefiles and / or implicit rules are used.
Thanks a lot for your help
PS: To clarify the first comments, I'm looking for a method which does not need to have a valid build environment (e.g. so compiling, even as a dry-run, is not an option).
is there a solution to know which sources files are responsible/used for the creation of a specific binary without compiling the project itself
If you compile with GCC (or perhaps Clang) you could use appropriate preprocessor options like -M to generate and keep in some textual file the dependencies, in a format acceptable by GNU make or ninja build automation tools. This works well on Linux distributions like Debian.
You could also be interested by other builders, including omake, and package managers like opam, urpmi, etc...
You could also be in touch with SoftwareHeritage team.
If you use GCC, you could write your own GCC plugin to maintain these dependencies in your database.
At last, be aware of Rice's theorem, and think about crazy examples (in C++) like
#if __TIME__[0]=='1'
int something=0;
#else
constexpr int something=1;
#endif
So my current intuition is that your wish is impossible. I could have misunderstood it.
Refer to some C standard like n1570, or to some C++ standard like n3337.
Study the behavior of tools like GNU autoconf.
Think of programs generating C or C++ code like GNU bison, my manydl.c, bismon, SWIG, RefPerSys, ANTLR .... Notice that GCC has many C++ code generators (notably gengtype) and is definitely "a complex project coded in C++".
See also linuxfromscratch.
How to write C program in VS2012 without using Microsoft specific extension C library?
For Example scanf_s() is Microsoft specific implementation. But if we use it we can't compile the code in Linux.
So should we use Linux VM in parallel the compile the code in gcc.
OR
we can setup gcc on windows.
OR
is there any better option or tweak in VS 2012 itself to achieve this?
Setting "Disable Language Extensions" just removes certain language features. A list of these features is here here.
However, extra functions provided by Microsoft aren't language features - they are just optional functions that are there if you want to use them. They are not disabled by that setting. The secure versions of standard functions, suffixed by _s, are in this category.
Having said that, if you navigate to the definition of scanf_s in the header, you can see that Microsoft have provided a way of disabling this particular family of functions.
If you define the following in your code before your header #includes
#define __STDC_WANT_SECURE_LIB__ 0
then scanf_s will no longer compile.
If you want to achieve this through your compiler switches, go to your project properties, and find the Preprocessor definitions. Add the following definition to the end:
__STDC_WANT_SECURE_LIB__#0
You can probably find similar ways to disable other additional Microsoft functions which are not part of 'standard' C.
I am implementing a proof of concept application for source-to-source transformation and need a C-parser with an API for manipulating/traversing the C-syntax tree (AST).
I have tried to use clang but I ran into various problems, like not being able to compile the tutorials using libclang, wrong architecture etc. Since this is a proof of concept application, I will defer clang to a different date.
Question
What are some software/libraries (implemented in any language) which can parse C code and which provide an API so I can build applications on top of them. I looked around, but I could not locate any free parsers.
The platforms I can use are anything on Windows or Mac or Linux, and any parsers written in C/C++/Java/Perl/Python/PHP will work.
You could try one of the available grammars for ANTLR. ANTLR has support for creating tree walkers and you can walk/manipulate the AST manually if necessary. ANTLR V3 has several grammars available including a C preprocessor, ANSI C and GNU C.
I work on the C code parser in Perl.
At the moment I need to pre-process the code.
Implementation of the pre-processing seems to be a lot of work, so I am looking for a script or library that will allow to pre-process the file.
I found the following possibilities:
Text::CPP
Filter::CPP
Both of these require cpp which I don't have on my Windows machine. Are there any other options?
I'm not sure I understand your needs, but you are right that implementing this yourself is probably a poor choice. I was recently looking for alternative C preprocessors as well.
The Text::CPP module should only require a compiler to compile itself. If you can find a precompiled version, it should work for you.
The JCPP Java C Preprocessor by the same author could probably be made to work. You'd likely have to process externally and then load the result.
Filepp is an older Perl program that claims CPP compatability. There is a precompiled Windows binary to download.
There is a brand new Lua C-Preprocessor LCPP that might be something you could work with. Probably best as a standalone, but you might be able to use Inline::Lua.
SWIG comes with its own preprocessor implementation. I presume this would be available for Windows.
What else? The Boost Wave Preprocessor might work well and is available for Windows.
The MSVC Compiler can preprocess to a file.
Still, the easiest and best long term solution may be to just install CPP. It comes as part of GCC, which you can get from Cygwin or MinGW.
I have implemented semaphores in Linux last year. But for that I have to use -lpthread.
Now while implementing log10() function in C, I surfed the INTERNET and I saw that I have to use -lm.
I want to know why these kind of command line arguments are necessary in Linux.And Does this rule is compiler oriented?
(In windows Turboc compiler, I never used these kind of arguments.)
You are instructing the compiler to look for certain libraries and use them to try and produce a final object file.
When you were doing your threading code, you used threading primitives. These threading primitives are implemented in a library called pthread, -lpthread tells the linker to use the library pthread, without providing this switch the compiler will not be able to produce a valid object file as it is missing threading code implementation.
On the file system the libraries can be found in /usr/lib and lib (among others) when you look in these directories you will see files start with the lib prefix. for example libpthreadxxxxxx. You will have to do your own research to figure out what the xxxx means.
The development cycle using unix style tools is very granular on the surface, when you use heavyweight IDE's (read: visual studiio for C++), the IDE implicetly links against loads of standard libraries, so often you do not need to supply the name of the libraries you will commonly use. However, when you start doing more advanced programming you will probably have to install and configure your IDE to use external code libraries. If you were to use threading primitives in visual studio, you most likely will not have to provide the compiler with information on where to look for threading primitives, Microsoft considers this a common library and every new project will implicitly link against it.
A little discussion on GCC
GCC is a very diverse compiler producing code for various different usage scenarios. As such they try to be neutral and do not make assumptions. For example pthread is a particular threading primitives implementation. However, even through now on Linux at least it is the defacto standard, it is not the only one. Other Unix implementation have had different implementation. When such choices exist it is not fair for the compiler developers to implicitly link against libraries. They do however implicitly link against standard libraries; for example G++ is just a wrapper command to the internal compiler code, it is a C++ front-end so it implicitly links against an implementation of the C++ standard library. Similarly the C front end links against a the standard C library.
People often do not want to use certain standard library implementation, and instead they might want to use another implementation, in such cases you have to explicetly inform the compiler to use an implementation that you provide. Such use cases are very granular and are surface level issues with G++. In visual studio, you would have to tinker a lot to make such changes generally, since it is not an anticipated use-case anymore.
wikipedia will provide you with more information.
Edit: I'll fix the spelling and Grammatical issues later :D
The option -l indicates to gcc what libraries must be used for linking. -lpthread stands for "use the pthread library", and -lm stands for "use the m library" which is the math library. These commands are relative to gcc, not linux.
Because by default, gcc only links the C library (libc), which contains the well-known functions printf, scanf, and many more.
log10 exists in a different library called libm, and thus you need to explictly tell gcc to link that library, with -lm. The same logic applies for -lpthread.
This is purely a backwards, harmful practice. Separating parts of the standard library into separate .so files does nothing but increase load time and memory usage. Good luck getting anyone to change it though... Just accept that you have to do it (and that POSIX specifically allows, but does not require, that an implementation require -lm for using the math functions and -lpthread for using threads, etc.) and move on to more important things.
Or, go pester Drepper about it on the glibc bug tracker/mailing list. He won't change his mind, but if you enjoy flamewars you can get some kicks...