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Word in a programming language that cannot be used as an identifier
In a computer language, a reserved word (also known as a reserved identifier) is a word that cannot be used as an identifier, such as the name of a variable, function, or label – it is "reserved from use". This is a syntactic definition, and a reserved word may have no user-defined meaning.
A closely related and often conflated notion is a keyword, which is a word with special meaning in a particular context. This is a semantic definition. By contrast, names in a standard library but not built into a language are not considered reserved words or keywords. The terms "reserved word" and "keyword" are often used interchangeably – one may say that a reserved word is "reserved for use as a keyword" – and formal use varies from language to language. For this article, we distinguish as above.
In general reserved words and keywords need not coincide, but in most modern languages keywords are a subset of reserved words, as this makes parsing easier, since keywords cannot be confused with identifiers. In some languages, like C or Python, reserved words and keywords coincide, while in other languages, like Java, all keywords are reserved words, but some reserved words are not keywords, being reserved for future use. In yet other languages, such as the older languages ALGOL, FORTRAN, and PL/I, there are keywords but no reserved words, with keywords being distinguished from identifiers by other means.
In a computer language, a reservedword (also known as a reserved identifier) is a word that cannot be used as an identifier, such as the name of a variable...
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titled by the United States Navy Register (C programming language), a reservedword (keyword) and type modifier Register (codebook), a codebook, a finite...
uses PERFORM VARYING. The name for-loop comes from the word for. For is used as the reservedword (or keyword) in many programming languages to introduce...
the possibility of implementing const, noticeable in that const is a reservedword, though it is not actually used as a keyword. Instead, Java has the...
self-documenting and highly readable. However, it is verbose and uses over 300 reserved words. This contrasts with the succinct and mathematically inspired syntax...
strictfp is an obsolete and redundant reservedword in the Java programming language. Previously, this keyword was used as a modifier that restricted...
function call a() Those reserved words can only be written lowercase and will not be recognized otherwise. The parent reservedword gives a reference to...
Synchronised (horse) (2003–2012), a racehorse synchronized, a programming reservedword that subjects a block of code to mutual exclusion, for thread safety...
compile time. If the developer creates a copy of an object using the reservedword clone, the Zend engine will check whether a __clone() method has been...
and semantic analysis. Lexing and parsing comprise the syntactic analysis (word syntax and phrase syntax, respectively), and in simple cases, these modules...
by including an additional condition for exit. a Eiffel supports a reservedword retry, however it is used in exception handling, not loop control. a...
with either a unique alias (such as a user-specified name) or an SGML reservedword (such as #DEFAULT). Entities are foundational to the organizational...
by making their names reserved words that cannot be used as folder or file names; for example: the word CON is a reservedword. These were chosen for...
method was marked with the dynamic or virtual directives. The inherited reservedword must be called when you want to call super-class behavior type TRectangle...
languages support the goto statement, and many do not. In Java, goto is a reservedword, but is unusable, although compiled .class files generate GOTOs and...
FORTRAN 90 Arrays and strings were inherited from FORTRAN 77, and a new reservedword was introduced: type type newtypet double precision a, b, c integer*2...
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