Next: character (System Class), Up: Characters [Contents][Index]
A character is an object that represents a unitary token (e.g., a letter, a special symbol, or a “control character”) in an aggregate quantity of text (e.g., a string or a text stream).
Common Lisp allows an implementation to provide support for international language characters as well as characters used in specialized arenas (e.g., mathematics).
The following figures contain lists of defined names applicable to characters.
The next figure lists some defined names relating to character attributes and character predicates.
|
Figure 13.1: Character defined names – 1
The next figure lists some character construction and conversion defined names.
|
Figure 13.2: Character defined names – 2
Next: Character Attributes, Previous: Introduction to Characters, Up: Character Concepts [Contents][Index]
A script is one of possibly several sets that form an exhaustive partition
of the type character.
The number of such sets and boundaries between them is implementation-defined. Common Lisp does not require these sets to be types, but an implementation is permitted to define such types as an extension. Since no character from one script can ever be a member of another script, it is generally more useful to speak about character repertoires.
Although the term “script” is chosen for definitional compatibility with ISO terminology, no conforming implementation is required to use any particular scripts standardized by ISO or by any other standards organization.
Whether and how the script or scripts used by any given implementation are named is implementation-dependent.
A
repertoire is a type specifier for a subtype of type character.
This term is generally used when describing a collection of characters
independent of their coding.
Characters in repertoires are only identified
by name,
by glyph, or
by character description.
A repertoire can contain characters from several scripts, and a character can appear in more than one repertoire.
For some examples of repertoires, see the coded character standards ISO 8859/1, ISO 8859/2, and ISO 6937/2. Note, however, that although the term “repertoire” is chosen for definitional compatibility with ISO terminology, no conforming implementation is required to use repertoires standardized by ISO or any other standards organization.
Next: Character Categories, Previous: Introduction to Scripts and Repertoires, Up: Character Concepts [Contents][Index]
Characters have only one standardized attribute:
a code. A character’s code is a non-negative integer.
This code is composed from a character script and a character label
in an implementation-dependent way. See the functions char-code and code-char.
Additional, implementation-defined attributes of characters are also permitted so that, for example, two characters with the same code may differ in some other, implementation-defined way.
For any implementation-defined attribute there is a distinguished value called the null value for that attribute. A character for which each implementation-defined attribute has the null value for that attribute is called a simple character. If the implementation has no implementation-defined attributes, then all characters are simple characters.
Next: Identity of Characters, Previous: Character Attributes, Up: Character Concepts [Contents][Index]
There are several (overlapping) categories of characters that have no formally associated type but that are nevertheless useful to name. They include graphic characters, alphabetic1 characters with case (uppercase and lowercase characters), numeric characters, alphanumeric characters, and digits (in a given radix).
For each implementation-defined attribute of a character, the documentation for that implementation must specify whether characters that differ only in that attribute are permitted to differ in whether are not they are members of one of the aforementioned categories.
Note that these terms are defined independently of any special syntax which might have been enabled in the current readtable.
Characters that are classified as graphic, or displayable, are each associated with a glyph, a visual representation of the character.
A graphic character is one that has a standard textual
representation as a single glyph, such as A or * or =.
Space, which effectively has a blank glyph, is defined
to be a graphic.
Of the standard characters, newline is non-graphic and all others are graphic; see Section 2.1.3 (Standard Characters).
Characters that are not graphic are called non-graphic. Non-graphic characters are sometimes informally called “formatting characters” or “control characters.”
#\Backspace,
#\Tab,
#\Rubout,
#\Linefeed,
#\Return, and
#\Page,
if they are supported by the implementation,
are non-graphic.
The alphabetic1 a subset of the graphic characters. Of the standard characters, only these are the alphabetic1
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
a b c d e f g h i j k l m n o p q r s t u v w x y z
Any implementation-defined character that has case must be alphabetic1 For each implementation-defined graphic character that has no case, it is implementation-defined whether that character is alphabetic1
The characters with case are a subset of the alphabetic1 A character with case has the property of being either uppercase or lowercase. Every character with case is in one-to-one correspondence with some other character with the opposite case.
An uppercase character is one that has a corresponding
lowercase character that is different
(and can be obtained using char-downcase).
Of the standard characters, only these are uppercase characters:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A lowercase character is one that has a corresponding
uppercase character that is different
(and can be obtained using char-upcase).
Of the standard characters, only these are lowercase characters:
a b c d e f g h i j k l m n o p q r s t u v w x y z
The uppercase standard characters A through Z mentioned above
respectively correspond to
the lowercase standard characters a through z mentioned above.
For example, the uppercase character E
corresponds to the lowercase character e, and vice versa.
An implementation may define that other implementation-defined graphic characters have case. Such definitions must always be done in pairs—one uppercase character in one-to-one correspondence with one lowercase character.
The numeric characters are a subset of the graphic characters. Of the standard characters, only these are numeric characters:
0 1 2 3 4 5 6 7 8 9
For each implementation-defined graphic character that has no case, the implementation must define whether or not it is a numeric character.
The set of alphanumeric characters is the union of the set of alphabetic1 and the set of numeric characters.
What qualifies as a digit depends on the radix
(an integer between 2 and 36, inclusive).
The potential digits are:
0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Their respective weights are 0, 1, 2, … 35.
In any given radix n, only the first n potential digits
are considered to be digits.
For example,
the digits in radix 2 are 0 and 1,
the digits in radix 10 are 0 through 9, and
the digits in radix 16 are 0 through F.
Case is not significant in digits;
for example, in radix 16, both F and f
are digits with weight 15.
Next: Ordering of Characters, Previous: Character Categories, Up: Character Concepts [Contents][Index]
Two characters that are eql, char=, or char-equal
are not necessarily eq.
Next: Character Names, Previous: Identity of Characters, Up: Character Concepts [Contents][Index]
The total ordering on characters is guaranteed to have the following properties:
char< is consistent with the numerical
ordering by the predicate < on their code attributes.
char=.
char-int to the
characters.
(char<= #\a x #\z)
is not a valid way of determining whether or not x is a
lowercase character.
Of the standard characters, those which are alphanumeric obey the following partial ordering:
A<B<C<D<E<F<G<H<I<J<K<L<M<N<O<P<Q<R<S<T<U<V<W<X<Y<Z a<b<c<d<e<f<g<h<i<j<k<l<m<n<o<p<q<r<s<t<u<v<w<x<y<z 0<1<2<3<4<5<6<7<8<9 either 9<A or Z<0 either 9<a or z<0
This implies that, for standard characters, alphabetic1 ordering holds within each case (uppercase and lowercase), and that the numeric characters as a group are not interleaved with alphabetic characters. However, the ordering or possible interleaving of uppercase characters and lowercase characters is implementation-defined.
Next: Treatment of Newline during Input and Output, Previous: Ordering of Characters, Up: Character Concepts [Contents][Index]
The following character names must be present in all conforming implementations:
NewlineThe character that represents the division between lines.
An implementation must translate between #\Newline,
a single-character representation, and whatever external representation(s)
may be used.
SpaceThe space or blank character.
The following names are semi-standard; if an implementation supports them, they should be used for the described characters and no others.
RuboutThe rubout or delete character.
PageThe form-feed or page-separator character.
TabThe tabulate character.
BackspaceThe backspace character.
ReturnThe carriage return character.
LinefeedThe line-feed character.
In some implementations,
one or more of these character names
might denote a standard character;
for example,
#\Linefeed and #\Newline might be the same character
in some implementations.
Next: Character Encodings, Previous: Character Names, Up: Character Concepts [Contents][Index]
When the character #\Newline is written to an output file,
the implementation must take the appropriate action
to produce a line division. This might involve writing out a
record or translating #\Newline to a CR/LF sequence.
When reading, a corresponding reverse transformation must take place.
Next: Documentation of Implementation-Defined Scripts, Previous: Treatment of Newline during Input and Output, Up: Character Concepts [Contents][Index]
A character is sometimes represented merely by its code, and sometimes
by another integer value which is composed from the code and all
implementation-defined attributes
(in an implementation-defined way
that might vary between Lisp images even in the same implementation).
This integer, returned by the function char-int, is called the
character’s “encoding.”
There is no corresponding function
from a character’s encoding back to the character,
since its primary intended uses include things like hashing where an inverse operation
is not really called for.
Previous: Character Encodings, Up: Character Concepts [Contents][Index]
An implementation must document the character scripts it supports. For each character script supported, the documentation must describe at least the following:
read treats
different characters as equivalent must be documented.
char-upcase,
char-downcase,
and the case-sensitive format directives.
In particular, for each character with case,
whether it is uppercase or lowercase,
and which character is its equivalent in the opposite case.
char-equal, char-not-equal,
char-lessp, char-greaterp,
char-not-greaterp, and char-not-lessp.
alpha-char-p,
lower-case-p,
upper-case-p,
both-case-p,
graphic-char-p,
and
alphanumericp.
Next: base-char, Previous: Character Concepts, Up: Characters [Contents][Index]
character,
t
A character is an object that represents a unitary token in an aggregate quantity of text; see Section 13.1 (Character Concepts).
The types base-char and extended-char
form an exhaustive partition of the type character.
Section 13.1 (Character Concepts), Section 2.4.8.1 (Sharpsign Backslash), Section 22.1.3.2 (Printing Characters)
Next: standard-char, Previous: character (System Class), Up: Characters [Contents][Index]
base-char,
character,
t
The type base-char is defined as the upgraded array element type
of standard-char.
An implementation can support additional subtypes of type character
(besides the ones listed in this standard)
that might or might not be supertypes of type base-char.
In addition, an implementation can define base-char
to be the same type as character.
Base characters are distinguished in the following respects:
standard-char is a subrepertoire of the type base-char.
base-char can be
elements of a base string.
base-char repertoire; the size of that repertoire
is
implementation-defined.
The lower bound is 96, the number of standard characters.
Whether a character is a base character depends on the way
that an implementation represents strings,
and not any other properties of the implementation or the host operating system.
For example, one implementation might encode all strings
as characters having 16-bit encodings, and another might have
two kinds of strings: those with characters having 8-bit
encodings and those with characters having 16-bit encodings. In the
first implementation, the type base-char is equivalent to
the type character: there is only one kind of string.
In the second implementation, the base characters might be
those characters that could be stored in a string of characters
having 8-bit encodings. In such an implementation,
the type base-char is a proper subtype of the type character.
The type standard-char is a
subtype of type base-char.
Next: extended-char, Previous: base-char, Up: Characters [Contents][Index]
standard-char,
base-char,
character,
t
A fixed set of 96 characters required to be present in all conforming implementations. Standard characters are defined in Section 2.1.3 (Standard Characters).
Any character that is not simple is not a standard character.
Section 2.1.3 (Standard Characters)
Next: char=; char/=; char<; char>; char<=; char>=; char-equal; char-not-equal+, Previous: standard-char, Up: Characters [Contents][Index]
extended-char,
character,
t
The type extended-char is equivalent to the type (and character (not base-char)).
The type extended-char might
have no elements4
in implementations in which all characters are of type base-char.
Next: character (Function), Previous: extended-char, Up: Characters [Contents][Index]
character—a character.
generalized-boolean—a generalized boolean.
These predicates compare characters.
char= returns true if all characters are the same;
otherwise, it returns false.
If two characters differ
in any implementation-defined attributes,
then they are not char=.
char/= returns true if all characters are different;
otherwise, it returns false.
char< returns true if the characters are monotonically increasing;
otherwise, it returns false.
If two characters
have identical implementation-defined attributes,
then their ordering by char< is
consistent with the numerical ordering by the predicate < on their codes.
char> returns true if the characters are monotonically decreasing;
otherwise, it returns false.
If two characters have
identical implementation-defined attributes,
then their ordering by char> is
consistent with the numerical ordering by the predicate > on their codes.
char<= returns true
if the characters are monotonically nondecreasing;
otherwise, it returns false.
If two characters have
identical implementation-defined attributes,
then their ordering by char<= is
consistent with the numerical ordering by the predicate <= on their codes.
char>= returns true
if the characters are monotonically nonincreasing;
otherwise, it returns false.
If two characters have
identical implementation-defined attributes,
then their ordering by char>= is
consistent with the numerical ordering by the predicate >= on their codes.
char-equal,
char-not-equal,
char-lessp,
char-greaterp,
char-not-greaterp,
and char-not-lessp
are similar to
char=,
char/=,
char<,
char>,
char<=,
char>=,
respectively,
except that they ignore differences in case and
might have an implementation-defined behavior
for non-simple characters.
For example, an implementation might define that
char-equal, etc. ignore certain
implementation-defined attributes.
The effect, if any,
of each implementation-defined attribute
upon these functions must be specified as part of the definition of that attribute.
(char= #\d #\d) → true (char= #\A #\a) → false (char= #\d #\x) → false (char= #\d #\D) → false (char/= #\d #\d) → false (char/= #\d #\x) → true (char/= #\d #\D) → true (char= #\d #\d #\d #\d) → true (char/= #\d #\d #\d #\d) → false (char= #\d #\d #\x #\d) → false (char/= #\d #\d #\x #\d) → false (char= #\d #\y #\x #\c) → false (char/= #\d #\y #\x #\c) → true (char= #\d #\c #\d) → false (char/= #\d #\c #\d) → false (char< #\d #\x) → true (char<= #\d #\x) → true (char< #\d #\d) → false (char<= #\d #\d) → true (char< #\a #\e #\y #\z) → true (char<= #\a #\e #\y #\z) → true (char< #\a #\e #\e #\y) → false (char<= #\a #\e #\e #\y) → true (char> #\e #\d) → true (char>= #\e #\d) → true (char> #\d #\c #\b #\a) → true (char>= #\d #\c #\b #\a) → true (char> #\d #\d #\c #\a) → false (char>= #\d #\d #\c #\a) → true (char> #\e #\d #\b #\c #\a) → false (char>= #\e #\d #\b #\c #\a) → false (char> #\z #\A) → implementation-dependent (char> #\Z #\a) → implementation-dependent (char-equal #\A #\a) → true (stable-sort (list #\b #\A #\B #\a #\c #\C) #'char-lessp) → (#\A #\a #\b #\B #\c #\C) (stable-sort (list #\b #\A #\B #\a #\c #\C) #'char<) → (#\A #\B #\C #\a #\b #\c) ;Implementation A → (#\a #\b #\c #\A #\B #\C) ;Implementation B → (#\a #\A #\b #\B #\c #\C) ;Implementation C → (#\A #\a #\B #\b #\C #\c) ;Implementation D → (#\A #\B #\a #\b #\C #\c) ;Implementation E
Should signal an error of type program-error if at least one
character is not supplied.
Section 2.1 (Character Syntax), Section 13.1.10 (Documentation of Implementation-Defined Scripts)
If characters differ in their code attribute
or any implementation-defined attribute,
they are considered to be different by char=.
There is no requirement that (eq c1 c2) be true merely because
(char= c1 c2) is true. While eq can distinguish two
characters
that char= does not, it is distinguishing them not
as characters, but in some sense on the basis of a lower level
implementation characteristic.
If (eq c1 c2) is true,
then (char= c1 c2) is also true.
eql and equal
compare characters in the same
way that char= does.
The manner in which case is used by
char-equal,
char-not-equal,
char-lessp,
char-greaterp,
char-not-greaterp,
and char-not-lessp
implies an ordering for standard characters such that
A=a, B=b, and so on, up to Z=z, and furthermore either
9<A or Z<0.
Next: characterp, Previous: char=; char/=; char<; char>; char<=; char>=; char-equal; char-not-equal+, Up: Characters [Contents][Index]
character—a character designator.
denoted-character—a character.
Returns the character denoted by the character designator.
(character #\a) → #\a (character "a") → #\a (character 'a) → #\A (character '\a) → #\a (character 65.) is an error. (character 'apple) is an error.
Should signal an error of type type-error if object is not a character designator.
(character object) ≡ (coerce object 'character)
Next: alpha-char-p, Previous: character (Function), Up: Characters [Contents][Index]
object—an object.
generalized-boolean—a generalized boolean.
Returns true if object is of type character;
otherwise, returns false.
(characterp #\a) → true (characterp 'a) → false (characterp "a") → false (characterp 65.) → false (characterp #\Newline) → true ;; This next example presupposes an implementation ;; in which #\Rubout is an implementation-defined character. (characterp #\Rubout) → true
character (Function) (type and function), typep
(characterp object) ≡ (typep object 'character)
Next: alphanumericp, Previous: characterp, Up: Characters [Contents][Index]
character—a character.
generalized-boolean—a generalized boolean.
Returns true if character is an alphabetic1
(alpha-char-p #\a) → true (alpha-char-p #\5) → false (alpha-char-p #\Newline) → false ;; This next example presupposes an implementation ;; in which #\α is a defined character. (alpha-char-p #\α) → implementation-dependent
None. (In particular, the results of this predicate are independent of any special syntax which might have been enabled in the current readtable.)
Should signal an error of type type-error if character is not a character.
alphanumericp, Section 13.1.10 (Documentation of Implementation-Defined Scripts)
Next: digit-char, Previous: alpha-char-p, Up: Characters [Contents][Index]
character—a character.
generalized-boolean—a generalized boolean.
Returns true if character is an alphabetic1
(alphanumericp #\Z) → true (alphanumericp #\9) → true (alphanumericp #\Newline) → false (alphanumericp #\#) → false
None. (In particular, the results of this predicate are independent of any special syntax which might have been enabled in the current readtable.)
Should signal an error of type type-error if character is not a character.
alpha-char-p, graphic-char-p, digit-char-p
Alphanumeric characters are graphic
as defined by graphic-char-p.
The alphanumeric characters are a subset of the graphic characters.
The standard characters A through Z,
a through z,
and 0 through 9 are alphanumeric characters.
(alphanumericp x) ≡ (or (alpha-char-p x) (not (null (digit-char-p x))))
Next: digit-char-p, Previous: alphanumericp, Up: Characters [Contents][Index]
weight—a non-negative integer.
radix—a radix.
The default is 10.
char—a character or false.
If weight is less than radix,
digit-char returns a character which has that weight
when considered as a digit in the specified radix.
If the resulting character is to be an alphabetic1
it will be an uppercase character.
If weight is greater than or equal to radix,
digit-char returns false.
(digit-char 0) → #\0 (digit-char 10 11) → #\A (digit-char 10 10) → false (digit-char 7) → #\7 (digit-char 12) → false (digit-char 12 16) → #\C ;not #\c (digit-char 6 2) → false (digit-char 1 2) → #\1
digit-char-p, graphic-char-p, Section 2.1 (Character Syntax)
Next: graphic-char-p, Previous: digit-char, Up: Characters [Contents][Index]
char—a character.
radix—a radix.
The default is 10.
weight—either a non-negative integer less than radix, or false.
Tests whether char is a digit in the specified radix
(i.e., with a weight less than radix).
If it is a digit in that radix,
its weight is returned as an integer;
otherwise nil is returned.
(digit-char-p #\5) → 5 (digit-char-p #\5 2) → false (digit-char-p #\A) → false (digit-char-p #\a) → false (digit-char-p #\A 11) → 10 (digit-char-p #\a 11) → 10 (mapcar #'(lambda (radix) (map 'list #'(lambda (x) (digit-char-p x radix)) "059AaFGZ")) '(2 8 10 16 36)) → ((0 NIL NIL NIL NIL NIL NIL NIL) (0 5 NIL NIL NIL NIL NIL NIL) (0 5 9 NIL NIL NIL NIL NIL) (0 5 9 10 10 15 NIL NIL) (0 5 9 10 10 15 16 35))
None. (In particular, the results of this predicate are independent of any special syntax which might have been enabled in the current readtable.)
Digits are graphic characters.
Next: standard-char-p, Previous: digit-char-p, Up: Characters [Contents][Index]
char—a character.
generalized-boolean—a generalized boolean.
Returns true if character is a graphic character; otherwise, returns false.
(graphic-char-p #\G) → true (graphic-char-p #\#) → true (graphic-char-p #\Space) → true (graphic-char-p #\Newline) → false
Should signal an error of type type-error if character is not a character.
read, Section 2.1 (Character Syntax), Section 13.1.10 (Documentation of Implementation-Defined Scripts)
Next: char-upcase; char-downcase, Previous: graphic-char-p, Up: Characters [Contents][Index]
character—a character.
generalized-boolean—a generalized boolean.
Returns true if character is of type standard-char;
otherwise, returns false.
(standard-char-p #\Space) → true (standard-char-p #\~) → true ;; This next example presupposes an implementation ;; in which #\Bell is a defined character. (standard-char-p #\Bell) → false
Should signal an error of type type-error if character is not a character.
Next: upper-case-p; lower-case-p; both-case-p, Previous: standard-char-p, Up: Characters [Contents][Index]
character, corresponding-character—a character.
If character is a lowercase character,
char-upcase returns the corresponding uppercase character.
Otherwise, char-upcase just returns the given character.
If character is an uppercase character,
char-downcase returns the corresponding lowercase character.
Otherwise, char-downcase just returns the given character.
The result only ever differs from character in its code attribute; all implementation-defined attributes are preserved.
(char-upcase #\a) → #\A (char-upcase #\A) → #\A (char-downcase #\a) → #\a (char-downcase #\A) → #\a (char-upcase #\9) → #\9 (char-downcase #\9) → #\9 (char-upcase #\@) → #\@ (char-downcase #\@) → #\@ ;; Note that this next example might run for a very long time in ;; some implementations if CHAR-CODE-LIMIT happens to be very large ;; for that implementation. (dotimes (code char-code-limit) (let ((char (code-char code))) (when char (unless (cond ((upper-case-p char) (char= (char-upcase (char-downcase char)) char)) ((lower-case-p char) (char= (char-downcase (char-upcase char)) char)) (t (and (char= (char-upcase (char-downcase char)) char) (char= (char-downcase (char-upcase char)) char)))) (return char))))) → NIL
Should signal an error of type type-error if character is not a character.
upper-case-p, alpha-char-p, Section 13.1.4.3 (Characters With Case), Section 13.1.10 (Documentation of Implementation-Defined Scripts)
If the corresponding-char is different than character, then both the character and the corresponding-char have case.
Since char-equal ignores the case of the characters it compares,
the corresponding-character is always the same as character
under char-equal.
Next: char-code, Previous: char-upcase; char-downcase, Up: Characters [Contents][Index]
character—a character.
generalized-boolean—a generalized boolean.
These functions test the case of a given character.
upper-case-p returns true if character is an uppercase character;
otherwise, returns false.
lower-case-p returns true if character is a lowercase character;
otherwise, returns false.
both-case-p returns true if character is a character with case;
otherwise, returns false.
(upper-case-p #\A) → true (upper-case-p #\a) → false (both-case-p #\a) → true (both-case-p #\5) → false (lower-case-p #\5) → false (upper-case-p #\5) → false ;; This next example presupposes an implementation ;; in which #\Bell is an implementation-defined character. (lower-case-p #\Bell) → false
Should signal an error of type type-error if character is not a character.
char-upcase, char-downcase, Section 13.1.4.3 (Characters With Case), Section 13.1.10 (Documentation of Implementation-Defined Scripts)
Next: char-int, Previous: upper-case-p; lower-case-p; both-case-p, Up: Characters [Contents][Index]
character—a character.
code—a character code.
char-code returns the code attribute of character.
;; An implementation using ASCII character encoding ;; might return these values: (char-code #\$) → 36 (char-code #\a) → 97
Should signal an error of type type-error if character is not a character.
Next: code-char, Previous: char-code, Up: Characters [Contents][Index]
character—a character.
integer—a non-negative integer.
Returns a non-negative integer encoding the character object.
The manner in which the integer is computed is implementation-dependent.
In contrast to sxhash, the result is not guaranteed to be independent
of the particular Lisp image.
If character has no implementation-defined attributes,
the results of char-int and char-code are the same.
(char= c1 c2) ≡ (= (char-int c1) (char-int c2))
for characters c1 and c2.
(char-int #\A) → 65 ; implementation A (char-int #\A) → 577 ; implementation B (char-int #\A) → 262145 ; implementation C
Next: char-code-limit, Previous: char-int, Up: Characters [Contents][Index]
code—a character code.
char-p—a character or nil.
Returns a character with the code attribute given by code.
If no such character exists and one cannot be created, nil is returned.
(code-char 65.) → #\A ;in an implementation using ASCII codes (code-char (char-code #\Space)) → #\Space ;in any implementation
The implementation’s character encoding.
Next: char-name, Previous: code-char, Up: Characters [Contents][Index]
A non-negative integer, the exact magnitude of which
is implementation-dependent, but which is not less
than 96 (the number of standard characters).
The upper exclusive bound on the value returned by
the function char-code.
The value of char-code-limit might be larger than the actual
number of characters supported by the implementation.
Next: name-char, Previous: char-code-limit, Up: Characters [Contents][Index]
character—a character.
name—a string or nil.
Returns a string that is the name of the character,
or nil if the character has no name.
All non-graphic characters are required to have names unless they have some implementation-defined attribute which is not null. Whether or not other characters have names is implementation-dependent.
The standard characters
<Newline> and <Space> have the respective names "Newline" and "Space".
The semi-standard characters
<Tab>, <Page>, <Rubout>, <Linefeed>, <Return>, and <Backspace>
(if they are supported by the implementation)
have the respective names
"Tab", "Page", "Rubout", "Linefeed", "Return", and "Backspace"
(in the indicated case, even though name lookup by “#\”
and by the function name-char is not case sensitive).
(char-name #\ ) → "Space" (char-name #\Space) → "Space" (char-name #\Page) → "Page" (char-name #\a) → NIL or→ "LOWERCASE-a" or→ "Small-A" or→ "LA01" (char-name #\A) → NIL or→ "UPPERCASE-A" or→ "Capital-A" or→ "LA02" ;; Even though its CHAR-NAME can vary, #\A prints as #\A (prin1-to-string (read-from-string (format nil "#\\~A" (or (char-name #\A) "A")))) → "#\\A"
Should signal an error of type type-error if character is not a character.
name-char, Section 22.1.3.2 (Printing Characters)
Non-graphic
characters having names are written by the Lisp printer
as “#\” followed by the their name; see Section 22.1.3.2 (Printing Characters).
Previous: char-name, Up: Characters [Contents][Index]
name—a string designator.
char-p—a character or nil.
Returns the character object whose name is
name (as determined by string-equal—i.e., lookup is not case sensitive).
If such a character does not exist, nil is returned.
(name-char 'space) → #\Space (name-char "space") → #\Space (name-char "Space") → #\Space (let ((x (char-name #\a))) (or (not x) (eql (name-char x) #\a))) → true
Should signal an error of type type-error if name is not a string designator.
Previous: char-name, Up: Characters [Contents][Index]