#! /usr/bin/env python
#
def ch_is_isbn_digit ( c ):

#*****************************************************************************80
#
## CH_IS_ISBN_DIGIT returns TRUE if the character C is an ISBN digit.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    15 September 2015
#
#  Author:
#
#    John Burkardt
#
#  Parameters:
#
#    Input, character C, the character to be checked.
#
#    Output, logical VALUE is TRUE if C is an ISBN digit.
#
  i0 = ord ( '0' )
  i9 = ord ( '9' )
  ic = ord ( c )

  if ( i0 <= ic and ic <= i9 ):

    value = True

  elif ( c == 'X' or c == 'x' ):

    value = True

  else:

    value = False

  return value

def ch_is_isbn_digit_test ( ):

#*****************************************************************************80
#
## CH_IS_ISBN_DIGIT_TEST tests CH_IS_ISBN_DIGIT.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    15 September 2015
#
#  Author:
#
#    John Burkardt
#
  import numpy as np
  import platform

  c_test = np.array ( [ 
    '0', '1', '2', '3', '4', \
    '5', '6', '7', '8', '9', \
    'X', 'x', 'Y', '*', '?', \
    ' ' ] )

  print ( '' )
  print ( 'CH_IS_ISBN_DIGIT_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  CH_IS_ISBN_DIGIT is TRUE if a character is an ISBN digit.' )
  print ( '' )
 
  for i in range ( 0, 16 ):
    c = c_test[i]
    value = ch_is_isbn_digit ( c )
    print ( '  "%c"  %s' % ( c, value ) )
#
#  Terminate.
#
  print ( '' )
  print ( 'CH_IS_ISBN_DIGIT_TEST:' )
  print ( '  Normal end of execution.' )
  return

if ( __name__ == '__main__' ):
  from timestamp import timestamp
  timestamp ( )
  ch_is_isbn_digit_test ( )
  timestamp ( )