Contents   Index   Previous   Next

2.6 String Literals

1
   [A string_literal is formed by a sequence of graphic characters (possibly none) enclosed between two quotation marks used as string brackets. They are used to represent operator_symbols (see 6.1), values of a string type (see 4.2), and array subaggregates (see 4.3.3). {quoted string: See string_literal} ]

Syntax

2
string_literal ::= "{string_element}"
3
string_element ::= "" | non_quotation_mark_graphic_character
4
A string_element is either a pair of quotation marks (""), or a single graphic_character other than a quotation mark.

Static Semantics

5
   {sequence of characters (of a string_literal)} The sequence of characters of a string_literal is formed from the sequence of string_elements between the bracketing quotation marks, in the given order, with a string_element that is "" becoming a single quotation mark in the sequence of characters, and any other string_element being reproduced in the sequence.
6
   {null string literal} A null string literal is a string_literal with no string_elements between the quotation marks.
NOTES
7
5  An end of line cannot appear in a string_literal.

Examples

8
   Examples of string literals:
9
"Message of the day:"

""    --  a null string literal
" "   "A"   """"      --  three string literals of length 1

"Characters such as $, %, and } are allowed in string literals"

Wording Changes from Ada 83

9.a
The wording has been changed to be strictly lexical. No mention is made of string or character values, since string_literals are also used to represent operator_symbols, which don't have a defined value.
9.b
The syntax is described differently.

Contents   Index   Previous   Next   Legal