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A string literal represents zero, two, or more characters and can take one of two different forms:

1. enclosed by single quotes (')
2. enclosed by double quotes (")

String Literals Enclosed By Single Quotes

String literals can be formed by enclosing, the characters being represented, in single quotes. NOTE: Single quote characters, in string literals enclosed in single quotes, are represented by a pair of single quote characters. So

   'Hello' represents the characters Hello

and

   'Don''t' represents the characters Don't

String literals are case-sensitive so 'Hello' is not equal to 'hello'.

NOTE: In Standard Pascal (ISO/IEC 7185) string literals must be enclosed in single quotes (').

String Literals Enclosed By Double Quotes

String literals can be formed by enclosing, the character being represented, in double quotes. NOTE: Double quote characters, in string literals enclosed by double quotes, are represented as a pair of double quote characters. So

   "Hello" represents the characters Hello

and

   """Hello""" represents the characters "Hello"

This second form of string literals, is an extension to Standard Pascal, and is provided mainly to make it easy to represent characters containing single quotes (i.e. you can enclose string literals containing single quotes with double quotes without using double single quotes like "'" instead of ''')'.

Examples

   ''     '   '  'Don''t'        'Say "Hello"'     '!@#$%^&*()'
   ""     "   "  "Don't"         "Say ""Hello"""   "!@#$%^&*()"

Syntax

   string-literal = empty-string | non-empty-string

   empty-string = '''' | '""'

   non-empty-string =
       ''' string-element-one string-element-one { string-element-one } ''' |
       '"' string-element-two string-element-two { string-element-two } '"'

   printable-character = any character (including a space) that has a visual representation.

   string-element-one = '''' | printable-character

   string-element-two = '""' | printable-character

NOTE: The production for printable-character doesn't use the usual notation because:

1. it's tedious to write out every possible printable character and
2. the definition for a printable character depends on the character set being used.