Character Constants

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Epsilon User's Manual and Reference

    Epsilon Extension Language

       . . .

       The EEL Preprocessor

       Lexical Rules

          Identifiers

          Numeric Constants

          Character Constants

          String Constants

       Scope of Variables

       . . .

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Epsilon User's Manual and Reference > Epsilon Extension Language > Lexical Rules >

Character Constants

Text enclosed in single quotes as in 'a' is a character constant. The type of a character constant is int. Its value is the ASCII code for the character. Instead of a single character, an escape sequence can appear between the quotes. Each escape sequence begins with a backslash, followed by a character from the following table. A backslash followed by any other character represents that character.

The special escape sequences are:

\n   newline character, ^J

\b   backspace character, ^H

\t   tab character, ^I

\r   return character, ^M

\f   form feed character, ^L

\yyy   character with ASCII code yyy octal

\xhh   character with ASCII code hh hexadecimal

\uhhhh   character with code hhhh hexadecimal

\u{h}   character with code h hexadecimal

\u[name]   character with given Unicode name

For example, '\'' represents the ' character, '\\' represents the \ character, '\0' represents the null character, and '\n', '\12', and '\x0A', all represent the newline character (whose ASCII code is 12 in octal notation, base 8, and 0A in hexadecimal, base 16).

The \u sequence is followed by four hex digits, while the \x sequence is followed by only two, and so can only represent low-numbered characters. Enclose the hex digits in curly braces to directly mark the end of the hex number; one to four hex digits can appear within. The square bracket syntax recognizes any standard Unicode character name, such as Greek Capital Letter Alpha. These sequences are all equivalent: \u[Greek Capital Letter Alpha], \u0391, \u{391}.

Anywhere a numeric constant is permitted, so is a character constant, and vice versa.

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