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From: doody@shrnew.enet.dec.com
Newsgroups: comp.lang.pascal
Subject: Re: VAX Pascal Question.  Somebody...
Message-ID: <4821@ryn.mro4.dec.com>
Date: 14 May 91 20:16:20 GMT
References: <1991May9.141955.3561@desire.wright.edu>
Sender: guest@ryn.mro4.dec.com
Reply-To: doody@shrnew.enet.dec.com ()
Organization: Digital Equipment Corporation
Lines: 72

In article <1991May9.141955.3561@desire.wright.edu>, bbehrmann@desire.wright.edu writes:
|>
|>	I've never used VAX Pascal before, stick with TP, but I am trying
|>to program something on a VMS system and am in need of a RANDOM number
|>function, and a function that allows you to execute VAX commands.  (Some
|>type of SHELL)  If anyone happens to know the answer, I'd greatly appriciate
|>it if you would let me know!!
|>Thanks!!
|>Talk to you later!!
|> 
|>                                  -Barry-
|>                        <BBEHRMANN@DESIRE.WRIGHT.EDU>
|>

Well, I have used VAX Pascal and TP. Both are great at what they do. For VAX
Pascal, You want to use the VMS RTL (run-time libraries). See $HELP RTL LIB$
and $ HELP RTL MTH$  (or much better, the hardcopy if you got em). 

For a 'shell' (really a command line interpreter in VMS lingo) You'll want to
use LIB$SPAWN. There are lots of options for LIB$SPAWN. You'll have to read the
docs for them all. The following fragment shows an example I've used to mail a
message (before the days of callable mail). Any DCL command could be used. 
Also you can specify a command file ( script ) to run instead of just a single 
command.

[ INHERIT('sys$library:starlet',
	  'sys$library:pascal$lib_routines' )]   
                  { need to INHERIT the routine declaration }

[...]

    VAR
	spawn_command		: varying [255] of char;
	spawn_status		: [volatile] unsigned; 
 { [volatile] because LIB$SPAWN is going to modify it behind Pascal's back...}

[...]

    spawn_status := 0;
    WRITEV( spawn_command, '$ mail/noself ', my_filename, mail_address );
    lib$spawn (
        command_string := spawn_command,
        completion_status_address := address(spawn_status) );
    if not odd( spawn_status )
    then
	begin
	{ error during the DCL command }
	end;



Here's a little example for random number generation. You'll have to come up
with an initial seed. Maybe generated from the current time or something.

[ INHERIT('sys$library:pascal$mth_routines' )]   

PROGRAM random ( OUTPUT );

    VAR
	random_number	: REAL;
	seed		: UNSIGNED;
	loop		: INTEGER;

    BEGIN
    {seed := routine_to_get_seed;}
    seed := 826495832;   { for example to run }
    FOR loop := 1 TO 10 DO
	BEGIN
	random_number := MTH$RANDOM ( seed );	
	WRITELN( 'Seed is ', Seed:11,'   random is ', random_number:0:11 );
	END;
    END.