Accessing command line arguments example doesn't work

I get wierd errors when I try to compile the command line argument example. First it had a problem with the line (ParamStr := ";), so I changed the " to " " Then it said ( cmdline.pas(36) Error: undeclared identifier `Arg_num'" )about the line ( Success := _p_paramstr (arg_num, Str);) I don't know what's wrong.

Here's the text I found in the Documentation of GPC: <********** begin text here *************>

Accessing command line arguments:

The following module accesses the command line with ParamStr and ParamCount functions.

These follow the Un*x semantics, so that

arg[0] == program name, arg[1] .. arg[ParamCount-1] are the arguments.

MODULE command_line interface;

EXPORT cmdline = (Max_length, Arg_type, ParamStr, ParamCount);

CONST Max_length = 255; { Max length of each argument. If some arg is longer, the run time system traps it. }

TYPE Arg_type = String(Max_length);

FUNCTION ParamCount: Integer;

FUNCTION ParamStr (arg_num: integer): Arg_type; END. { command_line interface }

MODULE command_line implementation;

{ These are in the GPC runtime library } FUNCTION _p_paramcount : Integer; C; FUNCTION _p_paramstr (num: Integer; VAR str: String): Boolean; C;

FUNCTION ParamCount; BEGIN ParamCount := _p_paramcount; END; { ParamCount }

FUNCTION ParamStr;

VAR Str : Arg_type; Success : Boolean;

BEGIN Success := _p_paramstr (arg_num, Str);

(* Should perhaps do something else on failure. * * Now it returns the empty string, which is also a valid * parameter. *) IF Success THEN ParamStr := Str else ParamStr := "; END; { ParamStr } END. { command_line implementation }

{ The program below, when compiled with the interface module and linked with the implementation module, accesses the command line arguments. }

program zap (output);

import cmdline;

var counter : integer;

begin writeln ('Program fetches command line arguments and outputs one per line'); writeln ('Max length of each argument is ',Max_Length:1,' characters');

for counter := 0 to ParamCount-1 do writeln ('Command line arg ',counter:1,' is "',paramstr(counter),'"'); end.

<******************end text here****************>

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