Swap 2 ints without using a 3rd variable

<b>Swap Two ints Without Using a Third Variable</b><br>
Here's an old trick from C, which carries over to <br>Java. If you have two ints a and b whose <br>values you want to swap, the obvious way to <br>do so is with a third, temporary variable: <br>
int c = a;<br>
a = b;<br>
b = c;<br>
It can be done without a temporary variable, <br>however, using Java's bitwise xor operator ^: <br>
a = a^b;<br>
b = a^b;<br>
a = a^b;<br>
The operator ^ produces a new int, each of whose <br>bits is the result of xor-ing the two <br>corresponding bits from the operands (1 if <br>the bits are different, 0 otherwise). To see why the trick works, consider the single-bit case <br>of a=1 and b=0. <br>
a = a^b = 1 xor 0 = 1<br>
b = a^b = 1 xor 0 = 1<br>
a = a^b = 1 xor 1 = 0<br>
Even though you initially overwrite the value of <br>a, no information is lost; its encoding <br>simply changes. In the case of larger (multi-bit)<br> numbers, each pair of bits will be swapped <br>in the same way, and so the entire int values are swapped. <br>
Finally, the swapping code can be made even more <br>succinct: 
<br>
a ^= b ^= a ^= b;<br>
Upload