What are Tri-Graph Characters?
https://www.computersprofessor.com/2016/05/what-are-tri-graph-characters.html
Many
non English keyboards do not support all the characters (some special symbols).
ANSI C introduces the concept of
‘Tri-graph’ sequences to provide a way to enter certain characters that are not
available on some keyboards.
Each tri-graph sequence consists of
3 characters (two question marks(??) Followed by another character).
For
ex; if a keyboard does not support square brackets, we can still use them in a
program using the tri-graphs.
Ex:
