In C/C++ there is only one right shift operator ‘>>’ which should be used only for positive integers or unsigned integers. Use of right shift operator for negative numbers is not recommended in C/C++, and when used for negative numbers, output is compiler dependent (See this). Unlike C++, Java supports following two right shift operators.
1) >> (Signed right shift) In Java, the operator ‘>>’ is signed right shift operator. All integers are signed in Java, and it is fine to use >> for negative numbers. The operator ‘>>’ uses the sign bit (left most bit) to fill the trailing positions after shift. If the number is negative, then 1 is used as a filler and if the number is positive, then 0 is used as a filler. For example, if binary representation of number is 10….100, then right shifting it by 2 using >> will make it 11…….1.
See following Java programs as example ‘>>’
class Test { public static void main(String args[]) { int x = -4; System.out.println(x>>1); int y = 4; System.out.println(y>>1); } } |
Output:
-2 2
2) >>> (Unsigned right shift) In Java, the operator ‘>>>’ is unsigned right shift operator. It always fills 0 irrespective of the sign of the number.
class Test { public static void main(String args[]) { // x is stored using 32 bit 2's complement form. // Binary representation of -1 is all 1s (111..1) int x = -1; System.out.println(x>>>29); // The value of 'x>>>29' is 00...0111 System.out.println(x>>>30); // The value of 'x>>>30' is 00...0011 System.out.println(x>>>31); // The value of 'x>>>31' is 00...0001 } } |
Output:
7 3 1
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