A "character constant" is formed by enclosing a single character from the representable character set within single quotation marks (' '). Character constants are used to represent characters in the execution character set.
Any member of the source character set except the single quotation mark ('), backslash (\), or newline character
\a \b \f \n \r \t \v
\' \" \\ \?
octal-digit octal-digit octal-digit