ISALPHA(3) Library Functions Manual ISALPHA(3)
NAME
isalphaalphabetic character test
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <ctype.h>
int
isalpha(int c);
DESCRIPTION
The isalpha() function tests for any character for which isupper(3) or islower(3) is true and for which none of iscntrl(3), isdigit(3), ispunct(3), or isspace(3) is true. In the ``C'' locale, isalpha() returns true only for the characters for which isupper(3) or islower(3) is true.
RETURN VALUES
The isalpha() function returns zero if the character tests false and returns non-zero if the character tests true.
SEE ALSO
STANDARDS
The isalpha() function conforms to ANSI X3.159-1989 (“ANSI C”).
CAVEATS
The argument to isalpha() must be EOF or representable as an unsigned char; otherwise, the behavior is undefined. See the CAVEATS section of ctype(3) for more details.