Trigraph sequences

Some characters from the C and C++ character set are not available in all environments. You can enter these characters into a C or C++ source program using a sequence of three characters called a trigraph. The trigraph sequences are:

Trigraph Single character capription
??= # pound sign
??( [ left bracket
??) ] right bracket
??< { left brace
??> } right brace
??/ \ backslash
??' ^ caret
??! | vertical bar
??- ~ tilde

The preprocessor replaces trigraph sequences with the corresponding single-character representation. For example,

some_array??(i??) = n;

Represents:

some_array[i] = n;