# shift ops!

ashok khetan

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Angela Narain

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Cameron Park

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Guoqiao Sun

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posted 14 years ago

Let's assume the right hand side operand is R, the left side operand is L.

For shift operation L SHIFT R, There will be a % operation if R is not inside the given range.

If L is int, the range is 0-32.

If L is long, the range is 0-64.

In that case, the result of the following

If L is int, R%32

If L is long, R%64

will be replaced for R.

Hope it helps.

------------------

Guoqiao Sun

Sun Certified Programmer for Java™ 2 Platform

Try my mock exam¹ at my homepage.

For shift operation L SHIFT R, There will be a % operation if R is not inside the given range.

If L is int, the range is 0-32.

If L is long, the range is 0-64.

In that case, the result of the following

If L is int, R%32

If L is long, R%64

will be replaced for R.

Hope it helps.

------------------

Guoqiao Sun

Sun Certified Programmer for Java™ 2 Platform

Try my mock exam¹ at my homepage.

Guoqiao Sun<br />SCJP2 SCWCD2<br />Creator of <a href="http://www.jiris.com/" target="_blank" rel="nofollow">www.jiris.com</a>, Java resource, mock exam, forum

Dave Vick

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Posts: 3244

posted 14 years ago

the actual operation carried out on the right hand operand is a bitwise & using a mask of 0x1F for ints and 0x3F for longs. For positive values this is the same as a %32 or %64, but for negative values it behaves differently. What it amounts to, at least in the few tests I've done, is that if the operand is greater than -32(for ints) it adds the operand to 32. So a shift of -4 would actually be a shift of 28. If the operand is less than -32 it will do a %32 on the operand then add the result (a negative number) to 32.

For a line like this:

54 >>> -34;

take -34%32, the result is -2, add -2 to 32, the result is 30, so the line could be written as:

54 >>> 30;

As a follow up, I dont think you'll see anything like this on the test - I didn't and dont know of anyone else who did.

hope this helped

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Dave

Sun Certified Programmer for the Javaï¿½ 2 Platform

For a line like this:

54 >>> -34;

take -34%32, the result is -2, add -2 to 32, the result is 30, so the line could be written as:

54 >>> 30;

As a follow up, I dont think you'll see anything like this on the test - I didn't and dont know of anyone else who did.

hope this helped

------------------

Dave

Sun Certified Programmer for the Javaï¿½ 2 Platform

Dave