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[[File:String example.png|alt=Diagram of String data in computing. Shows the word "example" with each letter in a separate box. The word "String" is above, referring to the entire sentence. The label "Character" is below and points to an individual box.|thumb|Strings are typically made up of [[character (computing)|characters]], and are often used to store human-readable data, such as words or sentences.]]
In [[computer programming]], a '''string''' is traditionally a [[sequence]] of [[character (computing)|characters]], either as a [[literal (computer programming)|literal constant]] or as some kind of [[Variable (computer science)|variable]]. The latter may allow its elements to be [[Immutable object|mutated]] and the length changed, or it may be fixed (after creation). A string
Depending on the programming language and precise data type used, a [[variable (programming)|variable]] declared to be a string may either cause storage in memory to be statically allocated for a predetermined maximum length or employ [[dynamic allocation]] to allow it to hold a variable number of elements.
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==History==
Use of the word "string" to mean any items arranged in a line, series or succession dates back centuries.<ref>{{cite encyclopedia |encyclopedia=The Oxford English Dictionary |volume=X |publisher=Oxford at the Clarendon Press |year=1933 |title=string }}</ref><ref>{{cite web |title=string (n.) |url=https://www.etymonline.com/search?q=string |website=Online Etymology Dictionary }}</ref> In 19th
Use of the word "string" to mean "a sequence of symbols or linguistic elements in a definite order" emerged from mathematics, [[symbolic logic]], and [[linguistic theory]] to speak about the [[formal system|formal]] behavior of symbolic systems, setting aside the symbols' meaning.<ref name=Burchfield1986>{{cite encyclopedia |title=string |encyclopedia=A Supplement to the Oxford English Dictionary |year=1986 |last=Burchfield |first=R.W. |publisher=Oxford at the Clarendon Press |author-link=Robert Burchfield }}</ref>
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=== String length ===
Although formal strings can have an arbitrary finite length, the length of strings in real languages is often constrained to an artificial maximum. In general, there are two types of string datatypes: ''fixed-length strings'', which have a fixed maximum length to be determined at [[compile time]] and which use the same amount of memory whether this maximum is needed or not, and ''variable-length strings'', whose length is not arbitrarily fixed and which can use varying amounts of memory depending on the actual requirements at run time (see [[Memory management]]). Most strings in modern [[programming languages]] are variable-length strings. Of course, even variable-length strings are limited in length by the amount of available memory. The string length can be stored as a separate integer (which may put another artificial limit on the length) or implicitly through a termination character,
=== Character encoding ===
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=== Implementations ===
{{anchor|String Buffers}}
Some languages, such as [[C++]], [[Perl]] and [[Ruby (programming language)|Ruby]], normally allow the contents of a string to be changed after it has been created; these are termed ''mutable'' strings.
Strings are typically implemented as [[array data type|arrays]] of bytes, characters, or code units,
Some languages, such as [[C (programming language)|C]], [[Prolog]] and [[Erlang (programming language)|Erlang]], avoid implementing a dedicated string datatype at all, instead adopting the convention of representing strings as lists of character codes. Even in programming languages having a dedicated string type, string can usually be iterated as a sequence character codes, like lists of integers or other values.
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