User Guide

74 Chapter 2: ActionScript Language Reference
<< (bitwise left shift)
Availability
Flash Player 5.
Usage
expression1
<< expression2
Parameters
expression1
A number or expression to be shifted left.
expression2 A number or expression that converts to an integer from 0 to 31.
Returns
A 32-bit integer.
Description
Operator (bitwise); converts expression1 and expression2 to 32-bit integers, and shifts all the
bits in
expression1 to the left by the number of places specified by the integer resulting from the
conversion of
expression2. The bit positions that are emptied as a result of this operation are
filled in with 0 and bits shifted off the left end are discarded. Shifting a value left by one position
is the equivalent of multiplying it by 2.
Floating-point numbers are converted to integers by discarding any digits after the decimal point.
Positive integers are converted to an unsigned hex value with a maximum value of 4294967295 or
0xFFFFFFFF; values larger than the maximum have their most significant digits discarded when
they are converted so the value is still 32-bit. Negative numbers are converted to an unsigned hex
value via the two’s complement notation, with the minimum being -2147483648 or
0x800000000; numbers less than the minimum are converted to two’s complement with greater
precision and also have the most significant digits discarded.
The return value is interpreted as a two’s complement number with sign, so the return value will
be an integer in the range -2147483648 to 2147483647.
For more information, see “Operator precedence and associativity” in Using ActionScript in Flash.
Example
In the following example, the integer 1 is shifted 10 bits to the left:
x = 1 << 10
The result of this operation is x = 1024. This is because 1 decimal equals 1 binary, 1 binary
shifted left by 10 is 10000000000 binary, and 10000000000 binary is 1024 decimal.
In the following example, the integer 7 is shifted 8 bits to the left:
x = 7 << 8
The result of this operation is x = 1792. This is because 7 decimal equals 111 binary, 111 binary
shifted left by 8 bits is 11100000000 binary, and 11100000000 binary is 1792 decimal.