Shyam Prasad Murarka

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Posts: 209

posted 12 years ago

Dear Readers,

I just learnt how to use binary operators from here.

I then took a look at the

I just learnt how to use binary operators from here.

I then took a look at the

**TicTacToe game**that comes in with JDK. Nearly everywhere they used left-shift operators or right-shift operators. I really can't understand it. Can anyone please explain the*logic of the game in a synopsis or pseudocode*. Please I can't get it through my thich brains.With Best Regards,

Shyam Prasad Murarka

posted 12 years ago

Consider the 3x3 square board as binary "switches" that can be turned on or off...

000

000

000

There are a total of 8 winning patterns -- since there are 3 rows, 3 columns, and 2 diagonals. For example, one way of winning is the bottom row...

000

000

111

If you string all of these switches together, you have a binary quantity, 000000111. One way to represent this quantity is using the

In the same manner, the middle row could be expressed as (1<<3) | (1<<4) | (1<<5). And the first

Each of these 8 winning patterns is initialized to "true" in the boolean array called "won." This array has an element representing

[ May 12, 2005: Message edited by: marc weber ]

000

000

000

There are a total of 8 winning patterns -- since there are 3 rows, 3 columns, and 2 diagonals. For example, one way of winning is the bottom row...

000

000

111

If you string all of these switches together, you have a binary quantity, 000000111. One way to represent this quantity is using the

*bitwise*"or" operator.*In binary,*000000111 = 000000001 | 000000010 | 000000100. A convenient way to express this is to use left-shift operators, (1<<0) | (1<<1) | (1<<2).In the same manner, the middle row could be expressed as (1<<3) | (1<<4) | (1<<5). And the first

*column*would be expressed as (1<<2) | (1<<5) | (1<<8).Each of these 8 winning patterns is initialized to "true" in the boolean array called "won." This array has an element representing

*each possible*pattern. The number of theoretical possibilities is 2^9 (two choices for each of the nine squares). 2^9 is equivalent to 1<<9 (binary), which is 512. So the boolean array of size 512 is created with "new boolean[1<<9]."[ May 12, 2005: Message edited by: marc weber ]

"We're kind of on the level of crossword puzzle writers... And no one ever goes to them and gives them an award." *~Joe Strummer*

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