Trigraph (orthography)

A Trigraph is a sequence of three symbols, for example, letters or numbers.

Linguistics

As a trigraph is known in linguistics a combination of three letters that are phonetically treated as a unit and represent a single sound. See also digraph (linguistics), Sch.

C programming

In the C programming nine three-character sequences are called trigraphs, all with? begin and are each used instead of a specific single character. They represent punctuation marks that are not available in different ASCII character sets, in particular national variants of ISO 646, or on certain keyboards could not be entered. However, the C programming language used almost the entire ASCII character set.

Today, hardly a need still exists for use of trigraphs or digraphs in C since on most keyboards all special characters are now available and ASCII or Unicode has become an established standard.