string comparison?

string comparison?

[Tri Tram]

	I am new to the ada programming language and I would appreciate it
if somebody could help me out with a couple of things.
1.  Is there anyway to do a string comparison in ada?
    So far, I have done it character by character but I am wondering if there
    is a better way to do it?  
2.  Is there anyway to exit out of a program inside an if-then-else statement?
    I have a program that waits for a command, and depending on that command,
    it would do something.  So I thought that the quit command would be 
    simplest.  But I can't even exit out of the if-then-else block.  

TIA.

-----------------------------------------------------------------
Tri Tram, Computer Science and Engineering at UCLA
http://www.seas.ucla.edu/~tram

Re: string comparison?

[Steve Doiel]

In article <EI5vIH.Et7@seas.ucla.edu>, tram@mulholland.seas.ucla.edu says...
>
>
>        I am new to the ada programming language and I would appreciate it
>if somebody could help me out with a couple of things.
>1.  Is there anyway to do a string comparison in ada?
>    So far, I have done it character by character but I am wondering if there
>    is a better way to do it? 

Sure, how about:

DECLARE
  ucToken : String := "CONST";
BEGIN
  IF ucToken = "CONST" THEN
    DoSomething;
  END IF;
END;

>2.  Is there anyway to exit out of a program inside an if-then-else 
statement?
>    I have a program that waits for a command, and depending on that command,
>    it would do something.  So I thought that the quit command would be 
>    simplest.  But I can't even exit out of the if-then-else block.

IF Ada.Characters.Handling.To_Upper( response ) = "QUIT" THEN
  RETURN;
END IF;

-- Since the main program in Ada is a procedure, you can RETURN to leave
-- the main procedure.

>
>TIA.
>
>-----------------------------------------------------------------
>Tri Tram, Computer Science and Engineering at UCLA
>http://www.seas.ucla.edu/~tram

Re: string comparison?

[Tom Moran]

>1.  Is there anyway to do a string comparison in ada?
>    So far, I have done it character by character but I am wondering if there
>    is a better way to do it?  
   subtype Punched_Cards is string(1 ..  80);
   a, b : Punched_Cards;
  ...
  if a = b then ...
 if a < b then ...

>2.  Is there anyway to exit out of a program inside an if-then-else statement?
>    I have a program that waits for a command, and depending on that command,
>    it would do something.  So I thought that the quit command would be 
>    simplest.  But I can't even exit out of the if-then-else block.
  If you want to exit a subroutine, you can do a 'return'.  If you
want to exit from a loop, use 'exit'.  I don't understand what you
might mean by being stuck inside an 'if' block.  Are you trying to
abort the whole program from deep inside some set of subroutines?
Perhaps you want to raise an exception, eg. "raise
Abandon_Ship_Every_Man_For_Himself".  Or do you want to go so far as
to reboot the computer, in which case you will need some OS call
specific to your target environment.   Or if this is an embedded
system and you want to trigger a booby-trap explosive device, the
method will depend on the target hardware.