function value ch_is_alphanumeric ( c )

%*****************************************************************************80
%
%% ch_is_alphanumeric is true if the character C is alphanumeric.
%
%  Discussion:
%
%    Alphanumeric characters are 'A' through 'Z', 'a' through 'z' and
%    '0' through '9'.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    22 February 2010
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    character C, the character to be checked.
%
%  Output:
%
%    logical VALUE, is TRUE if the character is alphabetic or numeric.
% 
  if ( ( 'a' <= i & i <= 'z' ) | ...
       ( 'A' <= i & i <= 'Z' ) | ...
       ( '0' <= i & i <= '9' ) )

    value = true;

  else

    value = false;

  end

  return
end
