-----------------------------------

Luffy123

Mon May 07, 2012 8:31 pm


:= and =?

-----------------------------------

What is the difference between the two?

I tried and it works still.

var num : int

num = 3
num := 3

both work.

the first one gets a warning though but still works.


-----------------------------------

Amarylis

Mon May 07, 2012 8:33 pm


RE::= and =?

-----------------------------------

The first one, while it does work, is supposed to be only for boolean expressions (comparison). The second one is the actual syntax for value assignment.


-----------------------------------

mirhagk

Mon May 07, 2012 10:03 pm


RE::= and =?

-----------------------------------

You should never use the first way, as within certain contexts it could be problematic (although those contexts  might not be common in Turing)


-----------------------------------

Raknarg

Tue May 08, 2012 11:03 am


RE::= and =?

-----------------------------------

Could you give us an example, mirhagk?


-----------------------------------

Tony

Tue May 08, 2012 12:22 pm


RE::= and =?

-----------------------------------

in C and such one might accidentally write code such as*
[code]
if (counter := 3) {
   % expecting counter to be 3
[/code]
instead the code _assigns_ 3 to the counter, and the result is evaluated to be true.

* actual C code uses == for comparison and = for assignment.


-----------------------------------

mirhagk

Tue May 08, 2012 3:24 pm


RE::= and =?

-----------------------------------

That is precisely what I was thinking of Tony. Although I'm trying to think of a way this could happen in Turing. Does turing set equal operator return the value? Is the following possible?

[syntax="turing']
var num1:=42
var num2:int
var num3:=num2:=num1
[/syntax]


-----------------------------------

evildaddy911

Tue May 08, 2012 3:50 pm


RE::= and =?

-----------------------------------

no, turing gives you a syntax error


-----------------------------------

mirhagk

Tue May 08, 2012 7:41 pm


RE::= and =?

-----------------------------------

so then I can't think of a context where it'd be an issue