Constants

Constants are tokens representing fixed numeric or character values.

The compiler supports four classes of constants: integer, floating point, character (including strings), and enumeration.

Internal representation of numerical types shows how these types are represented internally.

The data type of a constant is deduced by the compiler using such clues as numeric value and the format used in the source code. The formal definition of a constant is shown in the following table.

Constants: Formal Definitions

constant: floating-constant integer-constant numeration-constant character-constant	nonzero-digit: one of 1 2 3 4 5 6 7 8 9
floating-constant: fractional-constant <exponent-part> <floating-suffix> digit-sequence exponent-part <floating-suffix>	octal-digit: one of 0 1 2 3 4 5 6 7
fractional-constant: <digit-sequence> . digit-sequence digit-sequence . a b c d e f	hexadecimal-digit: one of 0 1 2 3 4 5 6 7 8 9 A B C D E F
exponent-part: e <sign> digit-sequence E <sign> digit-sequence	integer-suffix: unsigned-suffix <long-suffix> long-suffix <unsigned-suffix>
sign: one of -	unsigned-suffix: one of u U
digit-sequence: digit digit-sequence digit	long-suffix: one of l L
floating-suffix: one of f l F L	enumeration-constant: identifier
integer-constant: decimal-constant <integer-suffix> octal-constant <integer-suffix> hexadecimal-constant <integer-suffix>	character-constant c-char-sequence
decimal-constant: nonzero-digit decimal-constant digit	c-char-sequence: c-char c-char-sequence c-char
octal-constant: 0 octal-constant octal-digit	c-char: Any character in the source character set except the single-quote ('), backslash (\), or newline character escape-sequence.
hexadecimal-constant: 0 x hexadecimal-digit 0 X hexadecimal-digi hexadecimal-constant hexadecimal-digit	escape-sequence: one of the following \" \' \? \\ t \a \b \f \n \o \oo \ooo \r \t \v \Xh... \xh...