< Mercury Programming
Types
Char
A value of type 'char'
is a single unicode character (implemented using UTF8 encoding and so may occupy 1 to 4 bytes). There are several ways to specify a 'char'
as a literal value:
- As an ordinary character between single quotes, for example
'a'
- unless:- the character is a single quote, in which case use 4 single quotes:
''''
, or use 3 single quotes and with a backslash as the second character:'\''
. - the character is a backslash, in which case use 2 backslashes between single quotes:
'\\'
. - the character is the double quote, in which case put it between single quotes:
'”'
, or give it a leading backslash and put them between single quotes:'\”'
.
- the character is a single quote, in which case use 4 single quotes:
- As a hexadecimal value giving the Unicode code point (see Unicode) of the required character; the hexadecimal value must have a leading 'x', placed between '\' characters, which are in turn placed between single quotes, for example
'\x63\'
(equivalent to the character 'c').
- As an octal value giving the Unicode code point of the required character; the octal value must be placed between '\' characters, which are in turn placed between single quotes, for example
'\251\'
(equivalent to the character '©').
- As a 4 digit hexadecimal value giving the Unicode code point of the required character; the value must be prefixed with '\u', and the result placed between single quotes, for example
'\u00B5'
(equivalent to the Greek lower case character μ).
- As an 8 digit hexadecimal value giving the Unicode code point of the required character; the value must be prefixed with '\U', and the result placed between single quotes, for example
'\U000000B1'
(equivalent to the character '±'). Note that the highest allowed value is'\U0010FFFF'
.
- Several special characters can be specified as shown in the table below:
Character | Specified Using |
---|---|
beep | '\a' |
backspace | '\b' |
carriage return | '\r' |
form feed | '\f' |
tab | '\t' |
new line | '\n' |
vertical tab | '\v' |
A simple Mercury program demonstrating 'char'
literals is in Section A.1
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