PDF versions of the standard
As of 1st September 2014 September 2021, the best locations by price for the official C and C++ standards documents in PDF seem to be:
Non-PDF electronic versions of the standard
Print versions of the standard
Print copies of the standards are available from national standards bodies and ISO but are very expensive.
If you want a hardcopy of the C90 standard for much less money than above, you may be able to find a cheap used copy of Herb Schildt's book The Annotated ANSI Standard at Amazon, which contains the actual text of the standard (useful) and commentary on the standard (less useful - it contains several dangerous and misleading errors).
The C99 and C++03 standards are available in book form from Wiley and the BSI (British Standards Institute):
Standards committee draft versions (free)
The working drafts for future standards are often available from the committee websites:
If you want to get drafts from the current or earlier C/C++ standards, there are some available for free on the internet:
For C:
ANSI X3.159-198 (C89):
I cannot find a PDF of C89, but it is almost the same as C90. The only major differences are in the boilerplate and section numbering, although there are some slight textual differences
ISO/IEC 9899:1990 (C90):
(Almost the same as ANSI X3.159-198 (C89) except for the frontmatter and section numbering. There is at least one textual difference in section 6.5.7 (previously 3.5.7), where "a list" became "a brace-enclosed list". Note that the conversion between ANSI and ISO/IEC Standard is seen inside this document, the document refers to its name as "ANSI/ISO: 9899/99" although this isn't the right name of the later made standard of it, the right name is "ISO/IEC 9899:1990")
TC1 for C90: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n423.pdf
There isn't a PDF link for TC2 on the WG14 website, sadly.
ISO/IEC 9899:1999 (C99 incorporating all three Technical Corrigenda):
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf
An earlier version of C99 incorporating only TC1 and TC2:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf
Working draft for the original (i.e. pre-corrigenda) C99: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n843.htm (HTML) and http://www.dkuug.dk/JTC1/SC22/WG14/www/docs/n843.pdf (PDF).
Note that there were two later working drafts: N869 and N878, but they seem to have been removed from the WG14 website, so this is the latest one available.
List of changes between C89/C90 and C99: http://port70.net/~nsz/c/c89/c9x_changes.html
TC1 for C99 (only the TC, not the standard incorporating it): http://www.open-std.org/jtc1/sc22/wg14/www/docs/9899tc1/n32071.PDF
TC2 for C99 (only the TC, not the standard incorporating it): http://www.open-std.org/jtc1/sc22/wg14/www/docs/9899-1999_cor_2-2004.pdf
ISO/IEC 9899:2011 (C11):
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
ISO/IEC 9899:2011/Cor 1:2012 (C11's only technical corrigendum): This can be viewed at https://www.iso.org/obp/ui/#iso:std:iso-iec:9899:ed-3:v1:cor:1:v1:en but cannot be downloaded. It is the actual corrigendum, not a draft.
ISO/IEC 9899:2018 (C17/C18):
https://web.archive.org/web/20181230041359if_/http://www.open-std.org/jtc1/sc22/wg14/www/abq/c17_updated_proposed_fdis.pdf (N2176)
C2x work-in-progress - latest working draft as of 18th October 2020 (N2731):
http://www.open-std.org/JTC1/SC22/WG14/www/docs/n2731.pdf
For C++:
Note that these documents are not the same as the standard, though the versions just prior to the meetings that decide on a standard are usually very close to what is in the final standard. The FCD (Final Committee Draft) versions are password protected; you need to be on the standards committee to get them.
Even though the draft versions might be very close to the final ratified versions of the standards, some of this post's editors would strongly advise you to get a copy of the actual documents — especially if you're planning on quoting them as references. Of course, starving students should go ahead and use the drafts if strapped for cash.
It appears that, if you are willing and able to wait a few months after ratification of a standard, to search for "INCITS/ISO/IEC" instead of "ISO/IEC" when looking for a standard is the key. By doing so, one of this post's editors was able to find the C11 and C++11 standards at reasonable prices. For example, if you search for "INCITS/ISO/IEC 9899:2011" instead of "ISO/IEC 9899:2011" on webstore.ansi.org you will find the reasonably priced PDF version.
The site https://wg21.link/ provides short-URL links to the C++ current working draft and draft standards, and committee papers:
The current draft of the standard is maintained as LaTeX sources on Github. These sources can be converted to HTML using cxxdraft-htmlgen. The following sites maintain HTML pages so generated:
Tim Song also maintains generated HTML and PDF versions of the Networking TS and Ranges TS.
POSIX extensions to the C standard
The POSIX standard (IEEE 1003.1) requires a compliant operating system to include a C compiler. This compiler must in turn be compliant with the C standard, and must also support various extensions defined in the "System Interfaces" section of POSIX (such as the off_t
data type, the <aio.h>
header, the clock_gettime()
function and the _POSIX_C_SOURCE
macro.)
So if you've tried to look up a particular function, been informed "This function is part of POSIX, not the C standard", and wondered why an operating system standard was mandating compiler features and language extensions... now you know!
There is a draft version of POSIX.1-2008 at http://www.open-std.org/jtc1/sc22/open/n4217.pdf.
POSIX.1-2008 also had two technical corrigenda, the latter of the two being dated 2016. There is an online HTML version of the standard incorporating the corrigenda at https://pubs.opengroup.org/onlinepubs/9699919799.2016edition/ - though, again, I have had situations where the site's own search box wasn't good for finding information.
There is an online HTML version of POSIX.1-2017 at https://pubs.opengroup.org/onlinepubs/9699919799/ - though, again, I recommend using Google instead of that site's searchbox. According to the Open Group website "IEEE 1003.1-2017 ... is a revision to the 1003.1-2008 standard to rollup the standard including its two technical corrigenda (as-is)". Linux manpages describe it as "technically identical" to POSIX.1-2008 with Technical Corrigenda 1 and 2 applied. This is therefore not a major revision and does not change the value of the _POSIX_C_SOURCE
macro.
To give the short answer, macros are used for defining language syntax extensions to Common Lisp or Domain Specific Languages (DSLs). These languages are embedded right into the existing Lisp code. Now, the DSLs can have syntax similar to Lisp (like Peter Norvig's Prolog Interpreter for Common Lisp) or completely different (e.g. Infix Notation Math for Clojure).
Here is a more concrete example:
Python has list comprehensions built into the language. This gives a simple syntax for a common case. The line
divisibleByTwo = [x for x in range(10) if x % 2 == 0]
yields a list containing all even numbers between 0 and 9. Back in the Python 1.5 days there was no such syntax; you'd use something more like this:
divisibleByTwo = []
for x in range( 10 ):
if x % 2 == 0:
divisibleByTwo.append( x )
These are both functionally equivalent. Let's invoke our suspension of disbelief and pretend Lisp has a very limited loop macro that just does iteration and no easy way to do the equivalent of list comprehensions.
In Lisp you could write the following. I should note this contrived example is picked to be identical to the Python code not a good example of Lisp code.
;; the following two functions just make equivalent of Python's range function
;; you can safely ignore them unless you are running this code
(defun range-helper (x)
(if (= x 0)
(list x)
(cons x (range-helper (- x 1)))))
(defun range (x)
(reverse (range-helper (- x 1))))
;; equivalent to the python example:
;; define a variable
(defvar divisibleByTwo nil)
;; loop from 0 upto and including 9
(loop for x in (range 10)
;; test for divisibility by two
if (= (mod x 2) 0)
;; append to the list
do (setq divisibleByTwo (append divisibleByTwo (list x))))
Before I go further, I should better explain what a macro is. It is a transformation performed on code by code. That is, a piece of code, read by the interpreter (or compiler), which takes in code as an argument, manipulates and the returns the result, which is then run in-place.
Of course that's a lot of typing and programmers are lazy. So we could define DSL for doing list comprehensions. In fact, we're using one macro already (the loop macro).
Lisp defines a couple of special syntax forms. The quote ('
) indicates the next token is a literal. The quasiquote or backtick (`
) indicates the next token is a literal with escapes. Escapes are indicated by the comma operator. The literal '(1 2 3)
is the equivalent of Python's [1, 2, 3]
. You can assign it to another variable or use it in place. You can think of `(1 2 ,x)
as the equivalent of Python's [1, 2, x]
where x
is a variable previously defined. This list notation is part of the magic that goes into macros. The second part is the Lisp reader which intelligently substitutes macros for code but that is best illustrated below:
So we can define a macro called lcomp
(short for list comprehension). Its syntax will be exactly like the python that we used in the example [x for x in range(10) if x % 2 == 0]
- (lcomp x for x in (range 10) if (= (% x 2) 0))
(defmacro lcomp (expression for var in list conditional conditional-test)
;; create a unique variable name for the result
(let ((result (gensym)))
;; the arguments are really code so we can substitute them
;; store nil in the unique variable name generated above
`(let ((,result nil))
;; var is a variable name
;; list is the list literal we are suppose to iterate over
(loop for ,var in ,list
;; conditional is if or unless
;; conditional-test is (= (mod x 2) 0) in our examples
,conditional ,conditional-test
;; and this is the action from the earlier lisp example
;; result = result + [x] in python
do (setq ,result (append ,result (list ,expression))))
;; return the result
,result)))
Now we can execute at the command line:
CL-USER> (lcomp x for x in (range 10) if (= (mod x 2) 0))
(0 2 4 6 8)
Pretty neat, huh? Now it doesn't stop there. You have a mechanism, or a paintbrush, if you like. You can have any syntax you could possibly want. Like Python or C#'s with
syntax. Or .NET's LINQ syntax. In end, this is what attracts people to Lisp - ultimate flexibility.
Best Answer
Gary Knott's Interpreting Lisp is very nice. You may also try others, like Jim Mayfield's Lisp. There are probably lots of little Lisps out there...
You mentioned that you don't like C. Maybe you'd like Haskell -- in which case you could try "Write yourself a Scheme in 48 hours", an interesting tutorial (you get to write a Scheme interpreter in Haskell).
Update: I know that a Lisper would hardly feel comfortable using Haskell, but hey, it's much more comfortable than C (at least for me)! Besides that, HAskell has a good FFI, so it should be easy to use the Haskell-made Lisp-reader as a C-compatible library.
Update 2: If you want to use XLisp, as suggested by another user, you will probably need src/xlread.c (863 lines) and include/xlisp.h (1379 lines) -- but I could be wrong...
Update 3: If you use Gary Knott's Lisp (one single C file with 942 lines), the function signature is int32 sread(void). This would be my choie if I didn't need anything fancy (like read macros) or highly optimized (there is a PDF paper that describes how the code is implemented, so you won't have to find your way in a labyrinth). The documentation for the function is:
See that Gary's Lisp is old and you'll need to change it so it compiles. Instead of including linuxenv.h, include:
Also, it does not work in 64-bit machines (the documentation of sread should tell you why...)
Update 4: There's also the Scheme implementations by Nils Holm (there are books describing the internals)