ISCNTRL

  .  Summary

  iscntrl(int <c>);   Test for Control character (0-31 or 127)

  .  Description

  The functions listed above test an integer value and return a non-
  zero (TRUE) value if the test condition is satisfied, or a zero
  (FALSE) if it is not.

  Except for isascii, these functions give valid results only for in-
  teger values in the ASCII character set, that is, values for which
  isascii is true.

  .  Return Value

  A non-zero (TRUE) value is returned if the test condition is sat-
  isfied, a 0 (FALSE) value otherwise.