int isalpha ( int c );

<cctype>

Check if character is alphabetic

Checks if parameter c is either an uppercase or a lowercase alphabetic letter.

Notice that what is considered a letter may depend on the locale being used; In the default C locale, what constitutes a letter is what returns true by either isupper or islower.

For a detailed chart on what the different ctype functions return for each character of the standard ANSII character set, see the reference for the <cctype> header.

Parameters

c

Character to be checked, casted to an int, or EOF.

Return Value

Example

/* isalpha example */
#include <stdio.h>
#include <ctype.h>
int main ()
{
  int i=0;
  char str[]="C++";
  while (str[i])
  {
    if (isalpha(str[i])) printf ("character %c is alphabetic\n",str[i]);
    else printf ("character %c is not alphabetic\n",str[i]);
    i++;
  }
  return 0;
}

Output:

character C is alphabetic
character + is not alphabetic
character + is not alphabetic

See also