is this a Java bug x= x++

not a bug:

x = x++; // this says x = 0 and after you do the assignment increment x by 1
x = ++x; // this says increment x by 1 and then assign it to x

int x=0;
 x = x++;
 System.out.println(x); you will get 0, becuase this is post increment.

but :
x=++x ;
System.out.println(1); you will get 1, becuase this is pre increment.

And samething  happens in 'c'  too.

No. It is by design.

x = x++;

means that x is assigned the value of x and then x is incremented AFTERWARDS.

x = ++x;

would produce the answer 1 because x is incremented first and then assigned the value of x.

Whooosh ! Threee answers.

no, I know about the x++ and ++x.

Let analyse  x=x++;

x=x;
x++;

x should be ONE.

luu-

Yes this will be  1.
  x=x++; // x is 0
  x=x; // x is 0
  x++; // x has become 1,  this not an assignment

but if you write
x=x++; in place of x++ in the last line, you will get x=0.

no, I know about the x++ and ++x.

Let analyse  x=x++;

x=x;
x++;

x should be ONE.

luu-

No. That is wrong.

x = 0;
x = x;
x++;

is not the same as :

x = 0;
x = x++;

ok, then, what is the process of x= x++;

x = x++;

"means that x is assigned the value of x and then x is incremented AFTERWARDS."

AFTERWARDS, shouldn't it be ONE?
luu-

> in C++
> The result is ONE.

Have you tested that?
It's been a while since I wrote any C++ but from memory it would also be zero.

   int x = 0;
    x = x++;   // result: 0, x is not incremented    
 
    original value of x is saved (x0rig)
    x is incremented
    x0rig is assigned to x
    therefore, x will always equal original value

The unary++ takes precedence over the = operator.
The unary++ increments its operand but returns the previous
value of the operand for the evaluation of the expression.

yes, I tested in C++. X is ONE.
that is why I ask.
luu-

Well zero is certainly the correct result using Java.
According to C/C++ operator precedence I would expect the result to also be zero. I don't have a C++ compiler handy at the moment, but will test it out when I do.

Thank you all you experts for the clarification.  I encounter this on one of the test.  That is why I got confused.

luu-

everyone, just because the C++ compiler gives an answer (1) for the code DOES NOT justify the behavior of this piece of code to be a standard one (unless the ANSI C++ rules get changed). Java handles some stuff differently from C++. Ever wonder why it's called Java and not C+++?

This is the discussion on the other side of the fence if interested:

https://www.experts-exchange.com/questions/20558014/what-is-x-x.html

n_fortynine : Yes. I think that was the point we were making.

a) it is not a bug
b) it is normal and standard for java to do this
c) C++ and Java do things differently

and
d) the C++ behaviour is undefined in standard and thus compiler dependant