sponsored by:
OSdata.com: C  

OSdata.com

C

    For information on how to interface high level languages and assembly languages, seeassembly/high level language interface

general

    nature: procedural language

    history: Created in 1972 by Dennis Ritchie at Bell Laboratories (with assistance by Brian W. Kernighan). Intended for systems programming.

structure

    format: free form

lexical elements

    source code character set: A C compiler may use any character set that includes at least the following characters: the 52 upper case and lower case alphabetic characters ( A B C D E F G H I J K L M N O P Q R S T U V W X Y Z a b c d e f g h i j k l m n o p q r s t u v w x y z ), the 10 decimal digits ( 0 1 2 3 4 5 6 7 8 9 ), the blank or space character, and 29 designated graphic characters ( ! # % ^ & * ( ) - _ + = ~ [ ] \ | ; : ' " { } , . < > / ? ). Five formatting characters (backspace, horizontal tab, verticle tab, form feed, and carriage return) are often used in C (formatting characters are treated as spaces). The dollar sign ($) and the at sign (@) are also commonly used (but not required by the standard). Some form of line separator is required, but it doesn’t have to be an actual character or character sequence.

    execution character set: The execution character set for C is required to have the standard characters of the source code character set, plus a null character and a newline character. The null character must have the value 0 and is used to mark the end of strings. The newline character is used to divide character streams into lines during input or output. Run time libraries may convert between the newline character and some other character(s) (or lack of characters) during execution (such as compacting the carriage return/line feed combination into the newline character or generating the newline character at the end of a logical record or transforming between various record separators and the newline character).

    white space: White space in C includes the blank (space character), horizontal tab, end-of-line, vertical tab, form feed, and comments. White space is ignored by the compiler (except when required to separate tokens or when used in a character or string constant), and therefore can be used freely by the programmer to make the program easy for a human to read. Some implementations of C treat nonstandard source characters as either white space or line breaks.

    line termination: Each line in a C source program is terminated with an end-of-line character or character sequence. Optionally, certain formatting characters (such as carriage return, form feed or vertical tab) can also terminate lines. An empty line is a line that consists of only a terminating character or character sequence or white space and line termination. A logical source line can be continued past a line termination by using the backslash character (\) or the ANSI C trigraph ??/ immediately before the line termination. String constants and preprocessor command lines can cross line breaks through the use of logical source lines. In some implementations of C, tokens can also cross line breaks through the use of logical source lines.

    line length: Many C compilers impose a maximum line length (both for physical source lines and for logical source lines). ANSI C requires logical source lines of at least 509 characters.

    escape characters: The backslash character (\) is used as an escape character, allowing a programmer to include characters that would normally have a special meaning for the compiler.

    alternative characters: ANSI C includes nine trigraphs (three character sequences) for encoding required characters outside of the ISO 646-1083 Invariant Code Set. These trigraphs always start with two consecutive question marks. These are:

trigraph normal
??( [
??) ]
??< {
??> }
??/ \
??! |
??' ^
??- ~
??= #

    multibyte characters: ANSI C supports both wide characters and multibyte characters.

    Wide characters are binary characters that are more than one byte, typically used for expressing large alphabets.

    Multibyte characters are the external representation of a wide character, in either the source or exeuction character set.

    comments: Comments are started by the occurence of the two character sequence /* at any time other than within a character or string constant. Comments are terminated by the two character sequence */. ANSI C requires that comments be replaced with a single space character, but many C compilers remove comments without inserting a space character. Some non-UNIX C compilers allow “nestable comments”, which violates both original and ANSI C. To comment out large sections of a C program, use preprocessor commands:

        #if 0

            

        #endif

tokens

    A C compiler always collects characters into the longest possible tokens, even if the result is not valid C. White space always divides tokens. White space can be used to prevent misinterpretation of C source code (for example, x--y would be tokenized as the illegal x -- y [combining the two hyphens into a single token], while x - -y would be toeknized as the valid x - - y). White space must be used to separate an identifier, reserved word, integer constant, floating point constant from a following identifier, reserved word, integer constant, or floating point constant. Although ANSI C requires that comments be replaced by white space, many compilers don’t, which can lead to unwanted token merging.

    operators: C has 15 simple operators ( ! % ^ & * - + = ~ | . < > / ? ), 11 compound assignment operators ( += -= *= /= %= <<= >>= &= ^= |= == ), and 10 other compound operators ( -> ++ -- << >> <= >= != && || ).

    separators: C has 9 separator tokens ( ( ) [ ] { } , ; : ).

porting

    www.digital.com/info/porting_assistant “The Digital Porting Assistant (available for Digital UNIX 3.2, and shipped as part of the developer toolkit on Digital UNIX 4.0) is a graphical environment which aids in the porting process. In addition to doing lint-like checking of C and Fortran code, it also contains extensive on-line help regarding developing software on Digital UNIX.”w55

further reading: books:

If you want your book reviewed, please send a copy to: Milo, POB 1361, Tustin, CA 92781, USA.

Price listings are for courtesy purposes only and may be changed by the referenced businesses at any time without notice.

    C: A Reference Manual; 4th edition; by Samuel P. Harbison, Guy L. Steele; Prentice Hall Computer Books; December 1994; ISBN 0133262243; paperback; 455 pages; $34.36; REVIEW: I strongly recommend this book to working professionals. This is not a beginner’s book. Instead it a reference manual covering the details of the implementation of C on the entire range of platforms and compilers.


    The C Programming Language, 2nd edition; by Brian W. Kernighan, Dennis M. Ritchie; Prentice Hall; June 1988; ISBN 0131103628; Paperback; 274 pages; $40.00; written by the creators of C; used by CS 308-273A (Principles of Assembly Languages) at McGill University School of Computer Science


     Learn C on the MacIntosh; 2nd edition; by Dave Mark; Addison-Wesley Pub Co; October 1995; ISBN 0201484064; paperback (with CD-ROM); 474 pages; $27.96

    A Book on C: Programming in C; 4th edition; by Al Kelley, Ira Pohl; Addison-Wesley Pub Co; January 1998; ISBN 0201183994; paperback; 726 pages; $39.95


    Absolute Beginner’s Guide to C; 2nd edition; by Greg M. Perry; Sams; April 1994; ISBN 0672305100; paperback; $17.60


     Codewarrior Software Development Using Powerplant; by Jan L. Harrington; AP Professional; May 1996; ISBN 0123264227; paperback (with CD-ROM); 295 pages; $24.47

    C for Cobol Programmers: A Business Approach; by Jim Gearing; Carter Shanklin (Editor); Addison-Wesley Pub Co; August 1995; ISBN 0805316604; Paperback; $37.95

In Association with Amazon.com

If you want your book reviewed, please send a copy to: Milo, POB 1361, Tustin, CA 92781, USA.

related software

Price listings are for courtesy purposes only and may be changed by the referenced businesses at any time without notice.

We are working on providing a second source.

     Metrowerks CodeWarrior Discover Programming for Mac 5.0; C, C++, Java, and Pascal; PowerMac; $49.95


     Metrowerks CodeWarrior Discover Programming for Windows 5.0; C, C++, Java, and Pascal; Windows 95, Windows 98, Windows NT; $49.95


     Compton’s Learning Programming Made Easy; The Learning Company; C, Java, TRUCK, and BASIC; Windows 95, Windows 98; $29.95



geek humor

    “C references are NULL && void*” —Warwick Allison

    C: The language that combines the power of assembly language with the flexibility of assembly language.

    “C makes it easy to shoot yourself in the foot. C++ makes it harder, but when you do, it blows away your whole leg.” —Bjarne Stroustrup on C++

    “C is the Fortran of the 90s.”
“Wrong. C is the Fortran of the 70s.” —Norman Diamond

    “C++ is to C, as lung cancer is to lung.” —Clayton Cramer

    “C is not a big language, and it’s not well served by a big book.” —Brian W. Kernighan and Dennis M. Ritchie, in “The C Programming Language”, Prentice Hall, 1988


Donate now
or the mouse dies!!!

OSdata.com is a visitor supported educational web site

For more details, click here.

Note: Please mail donations to: Milo, PO Box 1361, Tustin, Calif, 92781, USA. The person who was taking the credit card donations kept all of the money that was donated via credit cards.


    A web site on dozens of operating systems simply can’t be maintained by one person. This is a cooperative effort. If you spot an error in fact, grammar, syntax, or spelling, or a broken link, or have additional information, commentary, or constructive criticism, please e-mail Milo. If you have any extra copies of docs, manuals, or other materials that can assist in accuracy and completeness, please send them to Milo, PO Box 1361, Tustin, CA, USA, 92781.

    Click here for our privacy policy.


previous page next page
previous page next page

home page

one level up

special topics

peer level


Enter your e-mail address to receive e-mail when this web page is updated.
Your Internet e-mail address:


Made with Macintosh

    This web site handcrafted on Macintosh computers using Tom Bender’s Tex-Edit Plus and served using FreeBSD .

Viewable With Any Browser


    Names and logos of various OSs are trademarks of their respective owners.

    Copyright © 1998, 2000, 2001 Milo

    Last Updated: March 23, 2001

    Created: August 25, 1998


OSdata.comMichael M, artistHypervue.com
previous page next page
previous page next page