islower()               Test for Lowercase (Macro)

 #include   <ctype.h>

 int        islower(c);
 int        c;                           Integer value to be tested

    islower() tests whether 'c' is lowercase ('a' - 'z').

       Returns:     True (nonzero) if the integer satisfies the test
                    condition or false (zero) if it does not.  The result
                    is undefined if 'c' is other than an ASCII character
                    or EOF.

         Notes:     islower() is a macro.

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

    The following statement tests whether the character read from a file
    is lowercase.

           #include <ctype.h>
           #include <stdio.h>               /* for fopen */

           int ch;
           FILE *stream;

           main()
           {
               if ((stream = fopen("input.dat","r+"))!= NULL) {
                   while (!feof(stream)) {
                       if (islower(ch = getc(stream)));
                    /* process character */
                   }
               }
           }