Flash MX 2004 Games : Art to ActionScript

Chapter 7: So what is a variable?
Binary numbers
These numbers use only the symbols 1 and 0. The value of the first column (furthest to the right) is
1, the second column is 2, the third is 4. Each column is double the previous. Therefore the binary
representation of 10 and 7 are
1010 (8 + 0 + 2 + 0)
0111 (0 + 4 + 2 + 1)
|(Or) operator
This combines the bits that make up the number. If either bit is set then the resulting bit is set.
1010 Or’ed with 0111 gives 1111 which is 8 + 4 + 2 + 1or15.
&(And) operator
This combines the bits that make up the number. If both bits are set then the resulting bit is set.
1010 And’ed with 0111 gives 0010, which is 0 + 0 + 2 + 0, or 2.
∧ (Xor) operator
This combines the bits that make up the number. If one bit is set but not both then the resulting
bit is set.
1010 Xor’ed with 0111 gives 1101, which is 8 + 4 + 0 + 1or13.
≪(left shift) operator
This moves the bits that make up the number.
1010 left shifted 7 places gives 10100000000 or 1024 + 0 + 256 or 1280.
≫(right shift) operator
This moves the bits that make up the number.
1010 right shifted 7 places gives 0000, the bits are left to zero after shifting only 4 places so
7 still leaves the result as zero.
All the operators that include the equals sign simply do the same but assign the result to the
variable on the left. ‘Examples/Chapter07/Variables03.fla’ shows all these operators in action. For
most programs in the book we will just be using the simple arithmetic operators but it is useful to
know how they all work.
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