array doubt: a [ (a = b)[3] ]

[Chandra Bhatt]

class Test
{
   public static void main(String[ ] args)
   {
      int[] a = { 1, 2, 3, 4 };
      int[] b = { 2, 3, 1, 0 };
      System.out.println( a [ (a = b)[3] ] ); [B]//LINE #1 [/B]
   }
}
 
What will it print when compiled and run ?

Please help me in understanding Line #1, I am not getting at all.


Source:
Enthuware

Thanks,

[sharan vasandani]

which version of enthuware are you using?

[sharan vasandani]

its printing 1 i dont know why?

[sharan vasandani]

i think when the compiler encounters
int[] b = { 2, 3, 1, 0 };
a[3] after solving inner part.


System.out.println( a [ (a = b)[3] ] );

due to first a which i have made bold at this point a is referring to this object { 1, 2, 3, 4 } then it solves the inner part due to which now
a[3] becomes 0,so the compiler sees 1 at index position 0 of the first array.

am not sure about this.

[Nik Arora]

Hi chandra,
Reference of b is passed to A. So, now a is refering to b. This was my observation.

int[] a = {1,2,3,4};
int[] b = {2,3,1,0};


System.out.println(a[ (a = b) [3] ] ); // prints 1
System.out.println(a[ (a = b) [2] ] ); //prints 2
System.out.println(a[ (a = b) [1] ] ); // prints 4
System.out.println(a[ (a = b) [0] ] ); //prints 3

Here the last element is printed as 3rd element and 3rd element is printed as last element but when you print "A" elements. It prints 2,3,1,0
because it is refering to b.Can anybody tell when the "B" reference is passed to "A" why is it printing like that?

[wong sheena]

Can anybody tell when the "B" reference is passed to "A" why is it printing like that?

(a=b) here the b address is being assigned to a.
so a is refering to b now.
meaning you can read like this a[ (a = b) [1] ] like a[ b [1] ]
now.

[Nik Arora]

Hi Wong,
Look at the statement below
Hi wong,

int[] a ={1,2,3,4};
int[] b={2,3,1,0};
System.out.println(a[ (a=b)[3] ]);

In this statement (a[ (a=b)[3] ]) when will the cast happen because output is 1. So as you explained the above statement will be a[b[3]] since b[3] returns "0" then the statement will be a[0] now since "A" is refering to "B" output should be 2 but why it is prinring 1.

[Jesse Custer]

More info on same question.

[Meena R. Krishnan]

int[] a ={1,2,3,4};
int[] b={2,3,1,0};

System.out.println(a[ (a=b)[3] ]);

a[(a=b)[3]] --> a[b[3]] --> a[0] --> 1

This is the first time I'm seeing such a question, very interesting!

[Srikanth Iyer]

HI the output of the code will be one

int[] a ={1,2,3,4};
int[] b={2,3,1,0};

System.out.println(a[ (a=b)[3] ]);

This exp will evaluate a=b first, so the reference of b will be passed on to a and b[3] that is 0 will inserted so the exp now becomes a[0] and the output will be 1.


I think this question was posted earlier too.