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A "string" is an array of characters. Strings are used for many
purposes in Emacs, as can be expected in a text editor; for example, as
the names of Lisp symbols, as messages for the user, and to represent
text extracted from buffers. Strings in Lisp are constants; evaluation
of a string returns the same string.
The read syntax for strings is a double-quote, an arbitrary number of
characters, and another double-quote, `"like this"'. The Lisp reader
accepts the same formats for reading the characters of a string as it
does for reading single characters (without the question mark that
begins a character literal). You can enter a nonprinting character such
as tab, `C-a' or `M-C-A' using the convenient escape sequences, like
this: `"\t, \C-a, \M-\C-a"'. You can include a double-quote in a
string by preceding it with a backslash; thus, `"\""' is a string
containing just a single double-quote character. (Note: Character
Type, for a description of the read syntax for characters.)
If you use the `\M-' syntax to indicate a meta character in a string
constant, this sets the 2**7 bit of the character in the string. This
is not the same representation that the meta modifier has in a
character regarded as a simple integer. Note: Character Type.
Strings cannot hold characters that have the hyper, super or alt
modifiers; they can hold ASCII control characters, but no others. They
do not distinguish case in ASCII control characters.
In contrast with the C programming language, Emacs Lisp allows
newlines in string literals. But an escaped newline--one that is
preceded by `\'--does not become part of the string; i.e., the Lisp
reader ignores an escaped newline in a string literal.
"It is useful to include newlines
in documentation strings,
but the newline is \
ignored if escaped."
=> "It is useful to include newlines
in documentation strings,
but the newline is ignored if escaped."
The printed representation of a string consists of a double-quote,
the characters it contains, and another double-quote. However, any
backslash or double-quote characters in the string are preceded with a
backslash like this: `"this \" is an embedded quote"'.
A string can hold properties of the text it contains, in addition to
the characters themselves. This enables programs that copy text between
strings and buffers to preserve the properties with no special effort.
Note: Text Properties. Strings with text properties have a special
read and print syntax:
where PROPERTY-DATA is zero or more elements in groups of three as
BEG END PLIST
The elements BEG and END are integers, and together specify a portion
of the string; PLIST is the property list for that portion.
Note: Strings and Characters, for functions that work on strings.
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