Contributor: SWAG SUPPORT TEAM
{
For you Programming librarians: the following Turbo Pascal Program
will verify any ISBN (International Standard Book Number).
}
(*******************************************************************)
Program VerifyISBN; { Verify any ISBN number. Turbo Pascal }
{ 1992, 1993 Greg Vigneault }
Var ISBNstr : String[16];
loopc, ISBNlen, M, chksm : Byte;
begin
WriteLn; WriteLn( 'ISBN Verification v0.1, Greg Vigneault',#10);
if ( ParamCount 1 ) then begin { we want just 1 input parm }
WriteLn( 'Syntax: ISBN ',#7 );
Halt(1);
end;
ISBNstr := ParamStr(1); { get ISBN# String }
Write( 'Checking ISBN# ', ISBNstr );
{ eliminate any non-digit Characters from the ISBN String... }
ISBNlen := 0;
For loopc := 1 to orD( ISBNstr[0] ) do
if ( ISBNstr[ loopc ] in ['0'..'9'] ) then begin
inC( ISBNlen );
ISBNstr[ ISBNlen ] := ISBNstr[ loopc ];
end;
{ an 'X' at the end of the ISBN affects the result }
if ( ISBNstr[ orD( ISBNstr[0] ) ] in ['X','x'] )
then M := 10
else M := orD( ISBNstr[ ISBNlen ] ) - 48;
ISBNstr[0] := CHR( ISBNlen ); { new ISBN str length }
chksm := 0;
For loopc := 1 to ISBNlen-1 do
inC( chksm, ( orD( ISBNstr[ loopc ] ) - 48 ) * loopc );
Write( ' <--- ' );
if ( ( chksm MOD 11 ) = M )
then WriteLn( 'Okay' )
else WriteLn( 'ERRor!',#7 );
end {VerifyISBN}.
(********************************************************************)