isalpha -- Alphabetic Character Test


SYNOPSIS
#include <ctype.h>
int isalpha(int c);
DESCRIPTION
isalpha
tests an integer value c
to determine whether it is an
alphabetic (uppercase or lowercase) character. In the C locale,
isalpha
returns true only for the characters for which isupper
or
islower
is true.
RETURN VALUE
isalpha
returns 0 if the character is not alphabetic, or a nonzero
value if it is alphabetic. If the argument is EOF
, 0 is returned.
CAUTIONS
The effect of isalpha
on a noncharacter argument other than EOF
is undefined. Do not assume that isalpha
returns either 0 or 1.
EXAMPLE
#include <ctype.h>
#include <stdio.h>
#define MAXLEN 40
main()
{
char id[MAXLEN+1];
int i;
char *text;
char input[MAXLEN];
puts("Enter a string (40 characters maximum). ");
text = gets(input);
puts("Initial alphabetic characters you entered:");
for (i = 0; i < MAXLEN && isalpha(text[i]); i++) {
id[i] = text[i];
putc(id[i]);
}
id[i] = '0';
putc('n');
}
RELATED FUNCTIONS
islower
, isupper
SEE ALSO