Originální popis anglicky:
isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower, isprint,
ispunct, isspace, isupper, isxdigit - character classification routines
Návod, kniha: Linux Programmer's Manual
#include <ctype.h>
int isalnum(int c);
int isalpha(int c);
int isascii(int c);
int isblank(int c);
int iscntrl(int c);
int isdigit(int c);
int isgraph(int c);
int islower(int c);
int isprint(int c);
int ispunct(int c);
int isspace(int c);
int isupper(int c);
int isxdigit(int c);
These functions check whether
c, which must have the value of an
unsigned char or
EOF, falls into a certain character class
according to the current locale.
- isalnum()
- checks for an alphanumeric character; it is equivalent to
(isalpha(c) || isdigit(c)).
- isalpha()
- checks for an alphabetic character; in the standard
"C" locale, it is equivalent to
(isupper(c) || islower(c)). In
some locales, there may be additional characters for which
isalpha() is true--letters which are neither upper case nor lower
case.
- isascii()
- checks whether c is a 7-bit unsigned char
value that fits into the ASCII character set. This function is a BSD
extension and is also an SVID extension.
- isblank()
- checks for a blank character; that is, a space or a
tab.
- iscntrl()
- checks for a control character.
- isdigit()
- checks for a digit (0 through 9).
- isgraph()
- checks for any printable character except space.
- islower()
- checks for a lower-case character.
- isprint()
- checks for any printable character including space.
- ispunct()
- checks for any printable character which is not a space or
an alphanumeric character.
- isspace()
- checks for white-space characters. In the
"C" and "POSIX" locales, these are:
space, form-feed ('\f'), newline ('\n'), carriage return
('\r'), horizontal tab ('\t'), and vertical tab
('\v').
- isupper()
- checks for an uppercase letter.
- isxdigit()
- checks for a hexadecimal digits, i.e. one of 0 1 2 3 4 5
6 7 8 9 a b c d e f A B C D E F.
The values returned are nonzero if the character
c falls into the tested
class, and a zero value if not.
ANSI - C, BSD 4.3.
isascii() is a BSD extension and is also an SVID
extension.
isblank() conforms to ISO C99 7.4.1.3.
The details of what characters belong into which class depend on the current
locale. For example,
isupper() will not recognize an A - umlaut as an
uppercase letter in the default
C locale.
setlocale(3),
tolower(3),
toupper(3),
ascii(7),
locale(7)
