isalpha

isalpha

Alphabetic Character Test

Portability: ISO/ANSI C conforming, UNIX compatible

SYNOPSIS
DESCRIPTION
RETURN VALUE
CAUTIONS
EXAMPLE
RELATED FUNCTIONS
SEE ALSO

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

Chapter 10, "Localization," in SAS/C Library Reference, Volume 2
Character Type Macros and Functions

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