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 | Description |
|---|---|---|
| ??= | # | 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;