Post Increment Operator

[mathiezhil]

When the piece of code given below when executed in java and c++
gives different results in java and c++.

class Test
{
public static void main(String args[])
{
int a=2;
System.out.println("a " + a);
a=a++;
System.out.println("a " + a);
a=++a;
System.out.println("a " + a);
}
}

the Output when run in java is :
a2
a2
a3.

in c++ it is :
a2
a3
a4
----------------
Was this implementation intentional in java.If so whats the reason.


Mathi Ezhil
(India)

[MarkN]

I don't know. But why are you doing that? Just do

int a=2;
System.out.println("a " + a);
a++;
System.out.println("a " + a);
++a;
System.out.println("a " + a);

[carl]

I would say that, in this particular case, java's interpretation of that code
makes more sense, and it doesn't matter anyway because the code is self-defeating.

In particular, "a=a++" means, increment 'a' but return the value before it
was incremented, assign that before-incremented value to 'a'. So the assignment
cancels the increment.

Perhaps the operator precidence rules are different between the two languages,
but it is a non-issue to me because the code is not just unrealistic; it
invites trouble.

Did you think that "a=a++" means the same thing as "a=a+1"? You probably
didn't, but if so, read some more about ++ and --.



"mathiezhil" <mathiezhil@rediffmail.com> wrote:
>
> When the piece of code given below when executed in java and c++
>gives different results in java and c++.
>
>class Test
>{
> public static void main(String args[])
> {
> int a=2;
> System.out.println("a " + a);
> a=a++;
> System.out.println("a " + a);
> a=++a;
> System.out.println("a " + a);
> }
>}
>
>the Output when run in java is :
>a2
>a2
>a3.
>
>in c++ it is :
>a2
>a3
>a4
>----------------
>Was this implementation intentional in java.If so whats the reason.
>
>
>Mathi Ezhil
>(India)

[Fotios]

It is very simple: C is right and Java is wrong.

a=++a; means:

1. a = a;
2. a = a + 1;



a=++a; means:

1. a = a + 1;
2. a = a;


The two statements in question are 2 sequential low level ops packed in a
single high level statement.

F.

[Fotios]

"Fotios" <fotios@altavista.net> wrote:
>
>It is very simple: C is right and Java is wrong.
>
>a=++a; means:

Sorry I meant a=a++; here

>
>1. a = a;
>2. a = a + 1;
>
>
>
>a=++a; means:
>
>1. a = a + 1;
>2. a = a;
>
>
>The two statements in question are 2 sequential low level ops packed in
a
>single high level statement.
>
>F.
>
>