• Thomas Kuehne (9/9) Nov 16 2004 Is the code below valid?
• Daniel Keep (9/21) Nov 16 2004 Ok, I could be wrong, BUT, I think that it's valid.
• Regan Heath (9/26) Nov 16 2004 Or, is the order reversed, i.e. assigns b to b, then a to b.
• Daniel Keep (5/41) Nov 17 2004 Hmm... my intuition tells me it's right to left. Assignment *should* be...

Thomas Kuehne <thomas-dloop kuehne.thisisspam.cn> writes:

Is the code below valid? 







The reason I ask is that this code passes the compiler,
but I can't find and documentation on it's behaviour.

Thomas

Daniel Keep <daniel.keep dummy.gmail.com> writes:

Ok, I could be wrong, BUT, I think that it's valid.

The trick here is that (unless Walter changed it from C/C++), assignment 
can be used in an expression.  Specifically, (a=b) first assigns the 
value of b to a, then returns a.

So `return b=b=a;' is assigning a to b, b to itself, then returning the 
value of b.

Maybe :P

	-- Daniel

Thomas Kuehne wrote:
 Is the code below valid? 
 





 
 The reason I ask is that this code passes the compiler,
 but I can't find and documentation on it's behaviour.
 
 Thomas

Regan Heath <regan netwin.co.nz> writes:

On Tue, 16 Nov 2004 19:11:30 +1100, Daniel Keep 
<daniel.keep dummy.gmail.com> wrote:

 Ok, I could be wrong, BUT, I think that it's valid.

 The trick here is that (unless Walter changed it from C/C++), assignment 
 can be used in an expression.  Specifically, (a=b) first assigns the 
 value of b to a, then returns a.

 So `return b=b=a;' is assigning a to b, b to itself, then returning the 
 value of b.

Or, is the order reversed, i.e. assigns b to b, then a to b.
Of course in both cases the result is the same, b=a.
The real question is, is the order defined?
If so, what is it?

Regan

 Thomas Kuehne wrote:






 The reason I ask is that this code passes the compiler,
 but I can't find and documentation on it's behaviour.

 Thomas




-- 
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

Daniel Keep <daniel.keep dummy.gmail.com> writes:

Hmm... my intuition tells me it's right to left.  Assignment *should* be 
right associative--it computes the right hand side first (thus, 
performing all the assignments right to left).

But then again, IANALL

Regan Heath wrote:
 On Tue, 16 Nov 2004 19:11:30 +1100, Daniel Keep 
 <daniel.keep dummy.gmail.com> wrote:
 
 Ok, I could be wrong, BUT, I think that it's valid.

 The trick here is that (unless Walter changed it from C/C++), 
 assignment can be used in an expression.  Specifically, (a=b) first 
 assigns the value of b to a, then returns a.

 So `return b=b=a;' is assigning a to b, b to itself, then returning 
 the value of b.

 
 
 Or, is the order reversed, i.e. assigns b to b, then a to b.
 Of course in both cases the result is the same, b=a.
 The real question is, is the order defined?
 If so, what is it?
 
 Regan
 
 Thomas Kuehne wrote:







 The reason I ask is that this code passes the compiler,
 but I can't find and documentation on it's behaviour.

 Thomas