Lateral thinking required

[Gazdaman]

Well, I've come up against a problem in one of my uni modules, they're using a theoretical programming language called "minimum Java"

It uses similar syntax, but knowing Java has nothing to do with it.

Basically, you can only have a while loop, i.e

while (y != 0) {
x = x + 1;
y = y - 1;

}


I've been asked to show that x = y, x = x + y and x = x-y.

I don't even know where to start with those!! If you know this kind of thing, it's very similar to a turing machine.

In a turing machine you'd change 1 thing to another to mark you've already been there.

But I just don't know..

Any suggestions or even vague ideas very much appreciated.

Gaz

[Walloper]

Eye don't know Y
____________________
W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[The View Askew]

all=0

It is the ONLY thing that could make sense. piss take
____________________
"Do what you always did, get what you always got"

[Hex]

Well if you show that x = whatever by the loop ending then it should just be a case of changing the condition on the loop, no?

For example:

x = 0
while (x != y) {
x = x + 1;
}
display x

Of course with y not been declared then you have the problem that it could be a negative number.

Is that the kind of thing your after?

As for showing x = x+y and x=x-y, then surely y can only be 0 as how could x = itself plus or minus anything else?
____________________
The BCF's very own Party boy! Though he's getting old and feeling it!
Monkey hanger, Born and bred
My little photo portfolio

[Gazdaman]

That's exactly what I thought Hex. But I wasn't sure, and in the documentation I'm pretty sure it states that while (x != 0) { } is the only while statement allowed.

Otherwise I agree, that way makes sense.

We have a /very/ chinese teacher, and hopefully she's neglected to mention we can in fact use x != y.

And thanks to everyone else that replied

Gaz

[Gazdaman]

In fact, I just had a thought.

It says you can't do x =y because that depends on the value of y.

I think what it wants you to do is:

x=0;
z=0;
while ( y != 0 ) {
y--;
x++;
z++;
}

while ( z != 0 ) {
z--;
y++;
}

If I'm correct, I think that should make x and y equal while staying within the rules.

It's all very simple stuff technically, it's just getting your head around the bastard.

Let this be a lesson to you guys! If you're faced with a list of modules to pick for your computing course don't pick "computer science concepts" because it looks interesting. It's hard!

Gaz