Difference in && and &=

[Joel]

Run this method:

public void test()
{
bool b;
int i=0;

b=false;
i=0;
b=(b && i++==1);
Console.WriteLine(i.ToString());

b=false;
i=0;
b&=i++==1;
Console.WriteLine(i.ToString());
}

Notice how in the first syntax, i++ is NOT evaluated (because of
short-circuit evaluation) but in the second syntax i++ is evaluated. I
wonder if this was intentional or an oversight. It burned me in a situation
when I was counting on short-circuit evaluation.

<joel>

 

[Chris R. Timmons]

Run this method:

public void test()
{
bool b;
int i=0;

b=false;
i=0;
b=(b && i++==1);
Console.WriteLine(i.ToString());

b=false;
i=0;
b&=i++==1;
Console.WriteLine(i.ToString());
}

Notice how in the first syntax, i++ is NOT evaluated (because of
short-circuit evaluation) but in the second syntax i++ is
evaluated. I wonder if this was intentional or an oversight. It
burned me in a situation when I was counting on short-circuit
evaluation.

Joel,

& and && are two completely different operators. & performs a
bitwise "and" of two numbers, but && is the boolean "and" operator.
Change the && to & and both code blocks return the same result (1).

 

[Xarky]

Joel,

& and && are two completely different operators. & performs a
bitwise "and" of two numbers, but && is the boolean "and" operator.
Change the && to & and both code blocks return the same result (1).

Is short-circuit evaluation the same as lazy evaluation?

 

[Chris R. Timmons]

(e-mail address removed) (Xarky) wrote in

in message



Is short-circuit evaluation the same as lazy evaluation?

http://en.wikipedia.org/wiki/Lazy_evaluation

and

http://en.wikipedia.org/wiki/Short_circuit

 

[Joel]

Yeah, I'm aware of the difference between & and && (and and and? ;-). Just
pointing out a 'gotcha' that 'gotme'.

</joel>