calculation question

[liqiang yang]

Hi there,

I sticked with this little one for a while:

int i = 4*6-3/2<<2*5>>>1%2-4^3;
System.out.println(i);

The answer is: 3

I try to do:
i=(24-3/2)<<(10)>>>(1%2-4)^3=23<<10>>>(-3)^3

then what's next?

3/2=1 and 1%2=1 right?

Can anybody give more detail info for next couple of calculation steps?

Thanks

[ramchandra sugasi]

hi,

the operator precedence for the operators available in java can be found at the following link:

http://java.sun.com/docs/books/tutorial/java/nutsandbolts/operators.html

From the table shown in the above link,

we can classify the precedences of the operators specific to the given expression "i = 4*6-3/2<<2*5>>>1%2-4^3" as follows:-

Note:- For simplicity, we assign numbers to the set of operators

Precedence Operator
---------- --------
1 * / %
2 -
3 << >>>
4 ^
5 =

Thus,
The given expression gets executed as:

Step1: * / % are executed
i = 24 - 1.5 << 10 >>> 1 - 4 ^ 3
Step2: - is executed
i = 22 << 10 >>> -3 ^ 3 // notice here that 22.5(24 - 1.5) becomes 22
Step3: << >>> are executed
i = 22528 >>> -3 ^ 3
i = 0 ^ 3 // when operators of equal precedence occur,left to right
// execution occurs. this idea can also be understood from
// the associativity property of each operator used in java
Step4:
i = 3

[liqiang yang]

Thanks ramchandra!

Sorry! I still confuse a little bit. Can you give more detail explain?

what rules applied on this : "22.5(24 - 1.5) becomes 22" and for 3/2 I think the division between integers, the result should get integer right?

how can get this done: "22 << 10 get 22528"
"22528 >>> -3 get 0"

[liqiang yang]

I already figured out : "22 << 10 get 22528"
But still confuse on "22.5(24 - 1.5) becomes 22" and "22528 >>> -3 get 0".

Can anyone help it out?

[liqiang yang]

I am still stick with this question. Need help!
Thanks.

[ramchandra sugasi]

hi,

the '<<' operator can be applied on integer arguments only.
thus,
The integer value of 22.5 is rounded off to 22.

'>>>' operator takes negative integer value which results
in a zero.

hence,
the answer is 3.

[liqiang yang]

Thanks. Sorry I am so fool.

But I put "(24-3/2)" in my compiler. Whatever I declare the results types like:

int x=(24-3/2); or
float x=(24-3/2);or
double x=(24-3/2);

The output prints are 23 or 23.0 but never are 22.5 or 22. That's why I'm still confusion. Sorry I am so fool.

[Varalakshmi Ramanarayan]

hi,

Do we need to know these things for SCJP 5? I think it has been removed from the objectives for SCJP 5.
Even K&B says that.
pls let me know if I am wrong.
Thanks.