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Topic: C language union


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In the News (Mon 28 May 12)

  
  Evolution of C   (Site not responding. Last check: 2007-10-23)
C began life in 1971 as a systems-programming language for the PDP-11 port of Unix, based on Ken Thompson's earlier B interpreter which had in turn been modeled on BCPL, the Basic Common Programming Language designed at Cambridge University in 1966-67.
Thus, the Version 6 C compiler was moved to the stricter definition-reference model (requiring at most one definition of any given public variable and the extern keyword tagging references to it) described in [Kernighan-Ritchie].
C standards development has been a conservative process with great care taken to preserve the spirit of the original C language, and an emphasis on ratifying experiments in existing compilers rather than inventing new features.
www.faqs.org /docs/artu/c_evolution.html   (1243 words)

  
  Union (computer science) - Wikipedia, the free encyclopedia
In C and C++, untagged unions are expressed nearly exactly like structures (structs), except that each data member begins at the same location in memory.
One common C programming idiom uses unions to perform what C++ calls a reinterpret_cast, by assigning to one field of a union and reading from another, as is done in code which depends on the raw representation of the values.
This is not, however, a safe use of unions in general, and is forbidden by the C language standard.
en.wikipedia.org /wiki/C_language_union   (632 words)

  
 C programming language article - C programming language C Programming Language Brian Kernighan Dennis Ritchie ...   (Site not responding. Last check: 2007-10-23)
C is prized for its efficiency, and is the most popular programming language for writing system software, though it is also used for writing applications.
C is a relatively minimalist programming language that operates close to the hardware, and is more similar to assembly language than most other programming languages.
By 1973, the C language had become powerful enough that most of the UNIX kernel, originally written in PDP-11/20 assembly language, was rewritten in C. This was one of the first operating system kernels implemented in a language other than assembly, earlier instances being the Multics system (written in PL/I) and TRIPOS (written in BCPL).
www.what-means.com /encyclopedia/C_programming_language   (4113 words)

  
 Greek language - Encyclopedia.WorldSearch   (Site not responding. Last check: 2007-10-23)
Two main forms of the language have been in use since the end of the medieval Greek period: Dhimotikí (Δημοτική), the Demotic (vernacular) language, and Katharévusa (Καθαρεύουσα), an imitation of classical Greek, which was used for literary, juridic, and scientific purposes during the 19th and early 20th centuries.
It is claimed that an "educated" speaker of the modern language can read the ancient dialects, but it is not made clear how much of that education consists of exposure to vocabulary and grammar obsolete to normal communication.
Greek is the official language of the Hellenic Republic (Greece) where it is spoken by about 98.5% of the population.
encyclopedia.worldsearch.com /greek_language.htm   (1531 words)

  
 washingtonpost.com: Police Union Disputes D.C. Crime Statistics
Union officials said they received a complaint that about 200 crime reports were set aside at the 7th Police District and never counted in crime statistics or were downgraded to lesser offenses.
Union officials said they conducted an audit of the reports and found that some crimes were never entered into databases, according to a letter delivered to Interim Inspector General Austin A. Andersen on Thursday.
Union officials said that by undercutting the number of crimes, the police department could give citizens a false sense of security.
www.washingtonpost.com /ac2/wp-dyn/A4481-2004Oct3?language=printer   (539 words)

  
 washingtonpost.com: Union, D.C. Hotels Recess Negotiations
Bruce S. Raynor, president of the national Unite Here union, acted as lead negotiator for Local 25 yesterday, demonstrating the degree to which the union views the negotiations in Washington as part of a national battle to increase labor's leverage against nationwide hotel chains.
Union officials, as they have since the contract covering hotel workers expired Sept. 15, said members may strike if they do not get their way.
The union argues that its members are overworked and often treated badly by their bosses, and that they want stronger protections in a contract.
www.washingtonpost.com /ac2/wp-dyn/A55137-2004Sep27?language=printer   (464 words)

  
 Union Declarations (C)   (Site not responding. Last check: 2007-10-23)
Unions are similar to "variant records" in other languages.
If a union of two types is declared and one value is stored, but the union is accessed with the other type, the results are unreliable.
Unions are often nested within a structure that includes a field giving the type of data contained in the union at any particular time.
msdn2.microsoft.com /en-us/library/y9zewe0d.aspx   (411 words)

  
 Re: C language portability support
C can be used to write portable programs that can run on anything from the largest supercomputers to tiny microcontrollers.
Secondly, integers in C don't have a predescribed implementation (like 2s complement, for example), so the int16_t on one platform doesn't have to behave the same way as it might on any other platform (except maybe having the same "sizeof").
C integer types in general aren't required to be 2sc, although hardware where they aren't is very rare indeed.
www.codecomments.com /message288703.html   (3091 words)

  
 Communications Programming Concepts - XDR Library Filter Primitives
Translates between C language unsigned integers and their external representations.
Translates between C language unsigned long integers and their external representations.
Translates between C language unsigned short integers and their external representations.
www.ncsa.uiuc.edu /UserInfo/Resources/Hardware/IBMp690/IBM/usr/share/man/info/en_US/a_doc_lib/aixprggd/progcomc/xdr_primit.htm   (1010 words)

  
 Chapter 3. C Language Changes
This is a pointed departure from traditional C, in which these members were nothing more than offsets, allowing you to use a member with a structure to which it does not belong.
This is not true in ANSI C. Note: Objects with external linkage that are not specified as extern at the end of the compilation unit are considered definitions, and, in effect, initialized to zero.
ANSI C rules for the promotion of arithmetic types when passing arguments to a function depend on whether or not a prototype is in scope for the function at the point of the call.
techpubs.sgi.com /library/dynaweb_docs/0530/SGI_Developer/books/CLanguageRef/sgi_html/ch03.html   (3478 words)

  
 C/C++ Language Reference   (Site not responding. Last check: 2007-10-23)
In C, a structure is composed of a set of data members.
In C++, a class type is like a C structure, except that a class is composed of a set of data members and a set of operations that can be performed on the class.
C++ allows you to redefine standard operators and functions through the concept of overloading.
www.nersc.gov /vendor_docs/ibm/vac/language/ref/classes.class.htm   (295 words)

  
 C Language Keywords
All data type keywords may be used in combination with asterisks, brackets and parentheses, for making complex data types, like pointer types, array types, function types, or combinations of them, which in the C language may have an arbitrary level of complexity (see asterisk for more info).
By default, the C language proposes that all uninitialized static variables are initialized to zero, but due to some limitations in TIGCC linker, you need to initialize explicitely all static and global variables if you compile the program in "nostub" mode.
A union is similar to a struct, except it allows you to define variables that share storage space.
tigcc.ticalc.org /doc/keywords.html   (2568 words)

  
 C language union   (Site not responding. Last check: 2007-10-23)
In the C programming language, a union is a datatype.
The space taken up by the union is the same as the largest of the individual types (plus padding) - and all the fields within the union have the same address as the union itself.
According to the C standard, it is invalid to read 'b' if 'a' was last written to, although on many implementations this gives useful behaviour.
www.portaljuice.com /c_language_union.html   (127 words)

  
 Language in India
As official language of the Union and several states, Hindi is used from the lowest unit of administration panchayat (village government) to the National Parliament, and has replaced English to a great extent.
It is a judicious and conscious decision of the founding fathers of the Constitution of India not to use the concept of "national language" (at least in the original which was drafted in English) in the Constitution and to opt for the word "official language of the Union".
The problems faced by a multilingual nation to settle upon a single language or a few languages as the official languages of the nation are quite different from the problems faced by the nations which have a clear dominant language of their own.
www.languageinindia.com /nov2004/mallikarjunmalaysiapaper1.html   (7630 words)

  
 DCE 1.1: Remote Procedure Call - IDL to C-language Mappings
The C types shown in the last column of the table are recommended definitions for the C defined types for 32-bit machines.
Unless specified otherwise, the code generated for the C language is syntactically identical to the IDL declarations.
The following are the mappings from IDL to the C language for which the syntax is not identical to IDL.
www.opengroup.org /onlinepubs/9629399/apdxf.htm   (584 words)

  
 udk: C UNO Language Specification
In contrast to sequences C arrays are not reference counted, thus copying big arrays may be time consuming.
UNO IDL Structs are generated to C typedefs to C structs declaring the C UNO types and members in the same order.
Unions will be generated as structs having a 64 bit discriminant as first member followed by a C union declaration.
udk.openoffice.org /cpp/man/spec/cuno_spec.html   (1336 words)

  
 Chapter 2. C Language Changes
However, because ANSI C considers a string literal to be an atomic unit, the expected substitution does not occur.
Function prototypes are not new to SGI C. In traditional C, however, the implementation of prototypes was incomplete.
Traditional C elicits an error diagnostic when the incompatibility may lead to a difference between the bit-pattern of the value passed in by the caller and the bit-pattern seen in the parameter by the callee.
techpubs.sgi.com /library/dynaweb_docs/0650/SGI_Developer/books/CLanguageRef/sgi_html/ch02.html   (3067 words)

  
 Dummies::Looking at the C Language
C programs can have many functions in them, though the main function is the first function in a C program.
The semicolon is how the C compiler knows when one statement ends and another begins — like a period at the end of a sentence.
Programming languages are similar to spoken language in that they have various parts and lots of rules.
www.dummies.com /WileyCDA/DummiesArticle/id-1062.html   (1028 words)

  
 C Programming Language Overview
C is a general-purpose programming language which features economy of expression, modern control flow and data structures, and a rich set of operators.
C is a typed language, but not so much a type-centered language (such as C++, which implements means to protect data accesses).
C source code mainly consists of code and data, and type definitions [mentioned in the previous chapter].
www.lrdev.com /lr/c/c-programming-language-overview.html   (2132 words)

  
 The C Programmig Language FAQ   (Site not responding. Last check: 2007-10-23)
A: When C requires the Boolean value of an expression (in the if, while, for, and do statements, and with the &&, , !, and ?: operators), a false value is inferred when the expression compares equal to zero, and a true value otherwise.
A: In C, characters are represented by small integers corresponding to their values (in the machine's character set), so you don't need a conversion routine: if you have the character, you have its value.
A: Under ANSI C, the text inside a "turned off" #if, #ifdef, or #ifndef must still consist of "valid preprocessing tokens." This means that there must be no newlines inside quotes, and no unterminated comments or quotes (note particularly that an apostrophe within a contracted word looks like the beginning of a character constant).
www-users.cs.umn.edu /~tan/www-docs/C_lang.html   (18119 words)

  
 5.1 C++ Review
C++ requires that function prototypes be provided for all functions before they are used and enforces consistent function use between program   files.
Like data elements of a C structure, member functions of a class can be accessed only through a reference to an object of the appropriate type.
As in C, a   class or structure can be included as a member of another class, hence   defining a has-a relationship between the two classes.
www.mcs.anl.gov /dbpp/text/node52.html   (1066 words)

  
 Brad Appleton's C++ Links
PERCEPS is a Perl script designed to parse C++ header files and automatically generate documentation in a variety of formats based on the class definitions and comment information found in those files.
ACACIA, the C++ Information Abstraction System, is a collection of analysis and reverse engineering tools for C++: CCia creates a program database from C++ source files to store information about C++ program entities (functions, variables, types, macros and files) and their relationships.
CIA, the C Information Abstraction System, is a collection of reverse enginnering tools for C: cia creates a program database from C source files to store information about C program entities (functions, variables, types, macros, and files) and their relationships.
www.cmcrossroads.com /bradapp/links/cplusplus-links.html   (1524 words)

  
 Chistory
C came into being in the years 1969-1973, in parallel with the early development of the Unix operating system; the most creative period occurred during 1972.
Within procedures, the language's interpretation of the pointers was identical to that of the array variables: a pointer declaration created a cell differing from an array declaration only in that the programmer was expected to assign a referent, instead of letting the compiler allocate the space and initialize the cell.
The language changes during this period, especially around 1977, were largely focused on considerations of portability and type safety, in an effort to cope with the problems we foresaw and observed in moving a considerable body of code to the new Interdata platform.
www.cs.bell-labs.com /cm/cs/who/dmr/chist.html   (8388 words)

  
 MIDDL to C language mapping
A new C type is defined for each MIDDL operation, which is a pointer to a C function returning a boolean value.
Under ANSI C, these function pointers are prototyped and should take as parameters a pointer to the binding being used, followed by the parameters of the operation, followed by the results the operation returned passed by reference.
Exceptions in MIDDL are mapped onto C functions in the server, and to an exception structure in the client.
www.cl.cam.ac.uk /Research/SRG/bluebook/16/msrpc2/node2.html   (1339 words)

  
 ISO/IEC JTC1/SC22/WG14 N794
Their characteristics define and constrain the results of executing conforming C programs constructed according to the syntactic and semantic rules for conforming implementations.
A structure or union type of unknown content (as described in 6.5.2.3) is an incomplete type.
Those bits of a structure or union object that are in the same byte as a bit-field member, but are not part of that member, shall similarly not affect whether the value of such an object is a trap representation.
www.vmunix.com /~gabor/c/draft.html   (11367 words)

  
 C++ Programming Language
C++ Programming Language is designed to teach the concepts of object-oriented design and implementation by examining abstract types, encapsulation, polymorphism, and inheritance.
In addition, the C++ programming language will be presented as a tool to produce object-oriented programs.
Upon completion of the course, students should be able to decompose basic programming problems by identifying the fundamental objects within the simulation, assigning relationship responsibilities, and testing for robustness.
cpd.ogi.edu /courseSpecific.asp?pam=995   (304 words)

  
 C++ Language Basics Part I
The C++ programming language can be thought of as a ``superset'' of the C language; that is, just about any legal Ansi C program is a legal C++ program, and means the same thing.
In C++ it is illegal to use a function without first declaring its type.
There are extra keywords in C++ that have no meaning in C. Since C++ is becoming prevalent, even when programming in C you should avoid the use of all of the following C++ keywords as function or variable names.
www.cs.cmu.edu /afs/cs.cmu.edu/academic/class/15211/spring.96/www/cxxbasics_one.html   (1334 words)

  
 C++ Language Notes
It does, however, describe the features of the language that are most useful to engineers and scientists.
Many commonly used features of C and C++ are defined in the standard libraries.
An expression involving operators of equal precedence is evaluated according to the associativity of the operators.
people.msoe.edu /~tritt/cpplang.html   (1205 words)

  
 Bison 1.25 - Parser C-Language Interface
Go to the first, previous, next, last section, table of contents.
If you use such an identifier (aside from those in this manual) in an action or in additional C code in the grammar file, you are likely to run into trouble.
When a token is referred to in the grammar rules by a name, that name in the parser file becomes a C macro whose definition is the proper numeric code for that token type.
dinosaur.compilertools.net /bison/bison_7.html   (1563 words)

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