Editing String literal (section)

==== Paired delimiters ====
A number of languages provide for paired delimiters, where the opening and closing delimiters are different. These also often allow nested strings, so delimiters can be embedded, so long as they are paired, but still result in delimiter collision for embedding an unpaired closing delimiter. Examples include [[PostScript]], which uses parentheses, as in <code>(The quick (brown fox))</code> and [[m4 (computer language)|m4]], which uses the [[backtick]] (`) as the starting delimiter, and the [[apostrophe]] (') as the ending delimiter. [[Tcl]] allows both quotes (for interpolated strings) and braces (for raw strings), as in <code>"The quick brown fox"</code> or <code>{The quick {brown fox}}</code>; this derives from the single quotations in Unix shells and the use of braces in [[C (programming language)|C]] for compound statements, since blocks of code is in Tcl syntactically the same thing as string literals – that the delimiters are paired is essential for making this feasible.

The [[Unicode]] character set includes paired (separate opening and closing) versions of both single and double quotations:
  “Hi There!”
  ‘Hi There!’
  „Hi There!“
  «Hi There!»

These, however, are rarely used, as many programming languages will not register them (one exception is the paired double quotations which can be used in [[Visual Basic .NET]]). Unpaired marks are preferred for compatibility, as they are easier to type on a wide range of keyboards, and so even in languages where they are permitted, many projects forbid their use for source code.