String: Difference between revisions

In APL, a '''string''' is a [[vector]] of [[character]]s. Strings are written using single quotes, for example <syntaxhighlight lang=apl inline>'string'</syntaxhighlight>.

A single character in quotes, such as <syntaxhighlight lang=apl inline>'a'</syntaxhighlight>, creates a [[scalar]] character rather than a string. To create a [[singleton]] string the [[ravel]] function is typically used, as in <syntaxhighlight lang=apl inline>,'a'</syntaxhighlight>. Ravelling a quoted literal always produces a string. This consideration only applies to exactly one character (or two quotes representing a single character, as described in the next paragraph); quotes with no characters between them (<syntaxhighlight lang=apl inline>''</syntaxhighlight>) form an [[empty]] string.

APL's string notation is very simple and includes only one [[wikipedia:Escape sequence|escape]]: two adjacent single quotes within a string stand for one single quote character rather than ending the string and starting a new one. To [[strand]] strings together, put spaces between them. A newline character within a string produces an error. To produce newlines or other non-printing characters which would be inconvenient to include in the source, use an alternative [[character]] creation mechanism, such as [[Unicode Convert]] (<syntaxhighlight lang=apl inline>⎕UCS</syntaxhighlight>).

Some users of [[Nested array model|nested]] APLs have proposed a dedicated [[string datatype]] to allow strings to be manipulated as a single entity, and in particular, to allow them to be compared with [[scalar function]]s. In [[Flat array model|flat]] APLs these problems are not felt so strongly because [[box]]ed arrays behave more like a simple datatype.

* [[wikipedia:String (programming)|String (programming)]]

{{APL features}}[[Category:Kinds of array]]