isalpha()               Test for Alphabetic Character (Macro)

 #include   <ctype.h>

 int        isalpha(c);
 int        c;                           Integer to be tested

    isalpha() tests whether 'c' is an alphabetic character; that is, if
    it is included in the set:

      'A'-'Z'  or  'a'-'z'.

       Returns:     True (nonzero) if the integer is in one of the sets,
                    and 0 if not. The result is undefined if 'c' is other
                    than an ASCII character or EOF.

         Notes:     isalpha() is a macro.

   -------------------------------- Example ---------------------------------

    The following statements get input from stdin, testing that only
    alphabetic characters are stored.

           #include <ctype.h>
           #include <stdio.h>

           int x = 0;
           char buffer[80];
           int ch;

           main()
           {
              while (isalpha(ch = getche()))
                    buffer[x++] = ch;
              printf("data input from console: %s \n",buffer);
           }