hi, a simple ?, if the right hand operand in a bit-shift expression is negative(e.g. 10 >> -2), then is there any separate rule for such calculations? ashok.
Joined: Apr 14, 2001
The shift distance for integer values is always in the range of 0 to 31 and for long values in the range of 0 to 63 .So you cannot possibily have a negative shift distance ! Correct me if wrong
Joined: Apr 06, 2001
I think shifting by negative value is actually shifting by their positive counterparts. For instance, 2>>-1 actually equals 2>>1111 1111 1111 1111, which eqauls 2>>31.
Joined: Jul 18, 2001
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.
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Joined: May 10, 2001
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
------------------ Dave Sun Certified Programmer for the Java� 2 Platform