ISALPHA(3) Linux Programmer's Manual ISALPHA(3)NAME
isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigit - character classifi-
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.
checks for an alphanumeric character; it is equivalent to (isalpha(c) || isdigit(c)).
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.
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.
checks for a blank character; that is, a space or a tab. This function is a GNU extension.
checks for a control character.
checks for a digit (0 through 9).
checks for any printable character except space.
checks for a lower-case character.
checks for any printable character including space.
checks for any printable character which is not a space or an alphanumeric character.
checks for white-space characters. In the "C" and "POSIX" locales, these are: space, form-feed ('f'), newline ('
'), horizontal tab (' '), and vertical tab ('v').
checks for an uppercase letter.
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() is a GNU extension.
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.
SEE ALSO tolower(3), toupper(3), setlocale(3), ascii(7), locale(7)GNU 1995-09-02 ISALPHA(3)