Digraphs and trigraphs

In computer programming, digraphs and trigraphs are sequences of two and three characters, respectively, that appear in source code and, according to a programming language’s specification, should be treated as if they were single characters.

Example

The C preprocessor replaces all occurrences of the nine trigraph sequences in this table by their single-character equivalents before any other processing.

TrigraphEquivalent
??=#
??/\
??’^
??([
??)]
??!|
??<{
??>}
??-~
DigraphEquivalent
<:[
:>]
<%{
%>}
%:#