ctype.3

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3 代码 · 共 115 行

.\" SCCSID: @(#)ctype.3	2.7	8/13/87
.TH ctype 3 
.SH Name
isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii \- character classification macros
.SH Syntax
.B #include <ctype.h>
.PP
.B int isalpha (\fIc\fP)
.PP
.B int c;
.SH Description
.NXR "ctype keyword"
.NXR "isalpha subroutine"
.NXR "isupper subroutine"
.NXR "islower subroutine"
.NXR "isdigit subroutine"
.NXR "isalnum subroutine"
.NXR "isspace subroutine"
.NXR "ispunct subroutine"
.NXR "isprint subroutine"
.NXR "isprint subroutine"
.NXR "isgraph subroutine"
.NXR "iscntrl subroutine"
.NXR "isascii subroutine"
.NXR "ASCII character" "classifying"
.PP
These macros classify character-coded integer values according to the rules of the coded character set (codeset) identified by the last successful call to
.PN setlocale
category
.PN LC_CTYPE .
All macros return non-zero for true and zero for false.
.PP
If
.PN setlocale
category
.PN LC_CTYPE
has not been called successfully, or if character classification information is not available for a supported language, then characters are classified according to the rules of the ASCII 7-bit coded character set, returning 0 for values above octal 0177.
.PP
The macro
.PN isascii 
provides a result for all integer values.
The rest provide a result for EOF and values in the character range of the codeset identified by the last successful call to
.PN setlocale
category
.PN LC_CTYPE .
.TP 15n
.PN isalpha
.I c
is a letter
.TP
.PN isupper
.I c
is an uppercase letter
.TP
.PN islower 
.I c
is a lowercase letter
.TP
.PN isdigit
.I c
is a digit
.TP
.PN isxdigit
.I c
is a hexadecimal digit, by default [0-9], [A-F], or [a-f]
.TP
.PN isalnum
.I c
is an alphanumeric character
.TP
.PN isspace
.I c
is a space, tab, carriage return, new line, or form feed
.TP
.PN ispunct
.I c
is a punctuation character (neither control, alphanumeric, nor space)
.TP
.PN isprint
.I c
is a printing character, by default code 040(8) (space) through 0176 (tilde)
.TP
.PN isgraph
.I c
is a printing character, like
.PN isprint
except false for space
.TP
.PN iscntrl
.I c
is a delete character (0177) or ordinary control character
(less than 040) except for space characters
.TP
.PN isascii
.I c
is an ASCII character, code less than 0200
.SS International Environment
.IP LC_CTYPE 15
If this environment variable is set and valid,
.PN ctype
uses the international language database named in the definition to 
determine character classification rules.
.IP LANG
If this environment variable is set and valid, 
.PN ctype
uses the international language database named in the definition to determine
the character classification rules. If 
.PN LC_CTYPE
is defined, that definition supercedes the definition of 
.PN LANG .
.SH See Also
conv(3), setlocale(3), stdio(3s), environ(5int), ascii(7)
.br
.I "Guide to Developing International Software"