String Constants¶

A string constant is a character string enclosed in single straight quotation marks. The characters are coded according to the character set specified in ISO/IEC 8859-1. Therefore, a string constant can include spaces and accented characters, as these belong to this character set. This is also referred to as a string literal, or simply a string.

Example: 'Hello world!'

When a dollar sign ($) is in a string constant, the following two characters are interpreted as a hexadecimal code according to the coding in ISO/IEC 8859-1. The code also corresponds to ASCII code. In addition, please note the special cases.

Hexadecimal code¶
String with $ code	Interpretation
`'$<8-bit code>'`	8-bit code: Two-digit hexadecimal number that is interpreted according to ISO/IEC 8859-1.
`'$41'`	`A`
`'$9A'`	`©`
`'$40'`	`@`
`'$0D'`	Control character: Line break (corresponds to ‘$R’)
`'$0A'`	Control character: New line (corresponds to ‘$L’ and ‘$N’)

Special cases¶
String with $ code	Interpretation
`'$L'`, `' $l'`	Control character: Line feed (corresponds to `'$0A'`)
`'$N'`, `'$n'`	Control character: New line (corresponds to `'$0A'`)
`'$P'`, `'$p'`	Control character: Form feed
`'$R'`, `'$r'`	Control character: Line break (corresponds to `'$0D'`)
`'$T'`, `'$t'`	Control character: Tab
`'$$'`	Dollar sign: `§`
`'$''`	Single straight quotation mark: `'`

Example

Constant declaration

VAR CONSTANT
    constA : STRING := 'Hello world';
    constB : STRING := 'Hello world $21'; // Hello world!
END_VAR