Mercury Programming/Types

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: '\”'. 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