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Metacharacters or function characters are characters in a file or character string that do not stand for themselves within a certain context, but, like control characters, have a special meaning for the processing of the data. The respective meaning of the metacharacters depends on the program with which the data is processed.

Often, non- alphanumeric characters are chosen as metacharacters. In order to be able to use metacharacters as pure characters in addition to their special meaning, rules for masking are often provided.



  • In XML , the following characters are metacharacters: <and &(at every position) as well as "or 'for attribute values.
  • When in Wikipedia used Wikitext example, has twice the square bracket , a term - in other words - the function of the term to another page within the Wikipedia link . The brackets are not displayed in the finished text, but are only noticeable when the relevant term is linked.[[Begriff]]

Programming languages

Within a programming language , metacharacters are the characters used for operators and separators . In C ajar and C programming languages such. B. C ++ , Java , PHP , Perl , Tcl , Python , Ruby , C # are z. B. mostly the characters ! " % & / ( ) = ? { [ ] } \ + * ~ < > | , ; . : - ^and 'defined as metacharacters.

Regular expressions

In a regular expression , metacharacters are characters that do not stand for themselves, but have a special meaning as an anchor, character class, quantifier, or something similar. In most regular expression implementations, the following characters are metacharacters:

  • ^ (Anchor for beginning [line or string])
  • $ (Anchor for end [line or string])
  • ? + * { } (Quantifiers or repetition factors)
  • \ (Changing the meta-status of a character [a meta-character loses its special meaning or a non-meta-character receives a special meaning])
  • . [ ] (Character classes)
  • & (Back reference)
  • ( ) (Grouping)
  • | alternative


  • When importing a CSV file in a spreadsheet program has a character (usually ,, ;or the tab ), the function of a separator which separates individual elements, so that the table to be imported these elements in different cells. The character itself does not appear in the finished table.
  • With EDIFACT , the EDI program is informed (in the optional UNA segment) which characters have the function of data element separator, segment separator, masking character and element group separator for this file . For a text editor, however , these characters have no function.

See also