Does C supports an equivalent of the triple-slash, XML Documentation Comments that Visual Studio uses to provide helpful tooltips for my code in C#, or am U just spoiled by being able to use them in C#?
If it's not supported in C, are there other options?
C does not have any equivalent of XML documentation comments or JavaDoc.
Try doxygen.
In the C language itself, a triple-slash comment is nothing special (they're just double-slash comments that happen to start with a slash).
However, you can use triple-slash comments with Doxygen.
Most modern C compilers will understand double-slash comments like in C++. They are part of the C99 spec.
Presumably you're talking about creating comment blocks that are formatted for automated extraction.
Doxygen supports special comment blocks that start with a double-slash C++ comment delimiter, followed by either another slash, or an exclamation mark.
C supports /* */ comments. C99 adds support for // comments. Your IDE or compiler may support more, but that is non-standard.
Related
From Programming Language Pragmatics by Michael Scott
Modern versions of C and C++ include a namespace mechanism
that provides module-like data hiding
Does C have namespaces similar to C++?
Are the "identifier name spaces" mentioned in C in a Nutshell the "namespaces" mentioned in Scott's book, and similar to namespaces in C++?
Thanks.
No, C does not have a namespace mechanism whereby you can provide “module-like data hiding”.
book quality
I do not know anything about the book you cited, but the word “namespaces” is one of those that gets overloaded to a lot of different meanings, just like “window”. (I question the validity of anything the author says for getting such a major point about one of the world’s oldest and most widespread computer languages so brazenly wrong.)
name spaces in C
“Name spaces” in C are a completely different mechanism, working for a completely different purpose. These are the name spaces discussed in “C in a Nutshell”. The words mean something different than C++ namespaces. Since David Rankin bothered to lookup chapter and section referencing the C11 Standard, these are the name spaces used in C:
label names
struct/union/enum tags
struct/union members
everything else (including enum values)
a quick blurb about scope
Keep in mind that this says nothing about scope, which is a separate mechanism. For example, a global variable and a variable local to a function may have the same name; nevertheless they share the same name space. The difference is that the global’s visibility is obscured by the local variable.
value of namespaces in C++
It is still unclear whether namespaces were a very useful extension to C++, and the argument as to its righteousness continues. The C crowd (mostly) agrees that the headache that adding namespaces would involve doesn’t justify the ends. I couldn’t find anything particularly useful on the interwebs right off the top of my keyboard, except for a couple of bland blurbs about emulating them using structs or (even worse) using macro abuse. If you really want to dig, you could probably find some useful discussions archived on the comp.lang.c newsgroup.
No, C has nothing like C++ namespaces. Most people have to fake what C++ does using a kind of underscore notation at best. This is at least what I do instead of trying to pack things into structs. Your IDE will still help with code assists, you just have to get used to using the underscore instead of a . for everything
C++
MyNamespace::MyObject.myMethodOrVar ...
Ends up looking like this in C
MyNamespace_MyObject_myMethodOrVar
May not be as smooth as C++ or Java, but it works and still helps avoid name collision. It's just a pain in the ass.
And yes, this doesn't give you syntactic devices like use. It is what it is I'm afraid.
I just read some glibc 2.22 source code (the source file at /sysdeps/posix/readdir.c) and came across this comment:
/* The only version of `struct dirent*' that lacks `d_reclen' is fixed-size. */
(Newline removed.)
The weird emphasis of the type and identifier bugs me. Why not use just single-quotes or des accents graves? Is there some specific reason behind this? Might it be some character set conversion mistake?
I also searched the glibc style guide but didn't found anything concerning code formatting in comments.
Convention.
As you no doubt know, comments are ignored by the C compiler. They make no difference, but the developer who wrote that comment probably preferred their appearance to plain single quotes.
ASCII
Using non-ASCII characters (unicode) in source code is a relatively new practice (moreso when English-authored source code is concerned), and there are still compatibility issues remaining in many programming language implementations. Unicode in program input/output is a different thing entirely (and that isn't perfect either). In program source code, unicode characters are still quite uncommon, and I doubt we'll see them make much of an appearance in older code like the POSIX header files for some time, yet.
Source code filters
There are some source code filters, such as document generation packages like the the well-known Javadoc, that look for specific comment strings, such as /** to open a comment. Some of these programs may treat your `quoted strings' specially, but that quoting convention is older than most (all?) of the source code filters that might give them special treatment, so that's probably not it.
Backticks for command substutution
There is a strong convention in many scripting languages (as well as StackExchange markdown!) to use backticks (``) to execute commands and include the output, such as in shell scripts:
echo "The current directory is `pwd`"
Which would output something like:
The current directory is /home/type_outcast
This may be part of the reason behind the convention, however I believe Cristoph has a point as well, about the quotes being balanced, similar to properly typeset opening and closing quotation marks.
So, again, and in a word: `convention'.
This goes back to early computer fonts, where backtick and apostrophe were displayed as mirror images. In fact, early versions of the ASCII standard blessed this usage.
Paraphrased from RFC 20, which is easier to get at than the actual standards like USAS X3.4-1968:
Column/Row Symbol Name
2/7 ' Apostrophe (Closing Single Quotation Mark Acute Accent)
6/0 ` Grave Accent (Opening Single Quotation Mark)
This heritage can also be seen in tools like troff, m4 and TeX, which also used this quoting style originally.
Note that syntactically, there is a benefit to having different opening and closing marks: they can be nested properly.
How to remove all C and C++ comments in vi?
//
/*
*/
You can't. Parsing C and C++ comments is not something that regular expressions can do. It might work for simple cases, but you never know if the result leaves you with a corrupted source file. E.g. what happens to this:
printf ("//\n");
The proper way is to use an external tool able to parse C. For example some compilers may have an option to strip comments.
Writing a comment stripper is also a basic exercise in lex and yacc programming.
See also this question: Remove comments from C/C++ code
With regular expressions, because of the complexity of C/C++ syntax, you will at best achieve a solution that is 90% correct. Better let the right tool (a compiler) do the job.
Fortunately, Vim integrates nicely with external tools. Based on this answer, you can do:
:%! gcc -fpreprocessed -dD -E "%" 2>/dev/null
Caveats:
requires gcc
it also slightly modifies the formatting (shrunk indent etc.)
Esc:%s/\/\///
Esc:%s/\/\*//
Esc:%s/\*\///
You can use a lexical analyzer like Flex directly applied to source codes. In its manual you can find "How can I match C-style comments?".
If you need an in-depth tutorial, you can find it here; under "Lexical Analysis" section you can find a pdf that introduce you to the tool and an archive with some practical examples, including "c99-comment-eater".
Coming from Java environment, I feel I got spoiled a lot when it comes to documentation. In C, using Eclipse, mouseover putchar() shows:
__CRT_INLINE int __cdecl __MINGW_NOTHROW putchar(int __c)
{
return (--stdout->_cnt >= 0)
? (int) (unsigned char) (*stdout->_ptr++ = (char)__c)
: _flsbuf (__c, stdout);}
While all this is terrific, I was wondering if any IDE includes more information about the specifics of what a given function does, ie, "prints a character to the output device"? Something similar to this as part of an IDE would be awesome.
Is there a way to get this level of detailed as part of Eclipse or any other IDE?
The question, obviously is not about putchar(), but rather is about a general approach to documentation using C programming language.
NetBeans will show you the man page inline: http://netbeans.org/kb/docs/cnd/navigating-editing.html
I don't have a solution for eclipse or an IDE, but my approach usually involves googling the function's manpage. eg, man putchar, which you've already found.
I'll also suggest this, at the risk of downvotes: The IBM C documentation is, in my experience, really good. Often it has real working understandable code examples and everything.
Now, IBM C is different from GNU C, so there are differences or features that do not apply to gcc. That said, Take a look at its page on the putchar() function.
There are plenty of things to complain about in C99, but it is still the authoritative reference and imo the best source for answers to the question, "what does it do?"
MS Visual Studio wraps a little skin around the C99 bones.
And MSDN goes further: docs on MSDN are beginning actually to resemble real papers by real writers that communicate useful info to a wide audience of neophytes and pros alike.
All credit goes to Let_Me_Be.
The following link provides a complete solution to what i was looking for
eclipse.org/linuxtools/projectPages/libhover
I'm looking for a parser for C. Here is what I need:
Written in C (not C++).
Handwritten (not generated).
BSD or similarly permissive license.
Capable of nontrivially parsing itself (can be a subset of C).
It can be part of a project as long as it's decoupled so that I can pull out the parser.
Is there an existing parser that fulfills these requirements?
If you don't need C99, then lcc is a slam dunk:
It is documented in a very clear, well-written book.
Techniques used for recursive-descent parsing of operators with precedence are well documented in an article and technical report by Dave Hanson.
Clear, handwritten ANSI C code.
One potential downside is that the lcc parser does not build an abstract-syntax tree—it goes straight from parsing to intermediate code.
If you must have C99 then I think tinycc (tcc) is your best bet.
How about Sparse?
You could try TCC. It's licensed under the Lesser GPL.
It seems that nwcc sufficiently agrees with your requirements.
Good c compiler is present at this location. Simple and accessible.
https://github.com/rui314/8cc
GCC has one in gcc/c-parser.c.
Check elsa, it uses the Generalized LR algorithm.
Its main use is for C++, but it also parses C code.
Check on its page, on the section called "How much C can Elsa parse?" which says it can parse most C programs, including the Linux kernel.
It's released under a BSD license.
Here is a recursive descent parser I ported to C:
http://www.gabotronics.com/resources/recursive-descent-parser.htm