The syntax for the
Imp operator is as follows
result = expression1 Imp expression2
where
expression1 and
expressions2 are any expressions and
result is any numeric variable.
When you use the
Imp operator to perform a bit-wise comparison of
identically positioned bits in two numeric expressions, the result of the
bit-wise comparison is determined using the rules in the following table.
Bit in Expression1 Bit in Expression2 Bit in Result
-------------------------------------------------------
1 1 1
1 0 0
0 1 1
0 0 1
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For example, if you run the following macro, a message box displays the
value of -11:
Sub Imp_Example()
Dim a As Integer
Dim b As Integer
Dim result As Integer
a =10
b = 4
result = a Imp b
MsgBox result
End Sub
The value -11 is returned because the macro follows the rules in the table
and uses
twos complement notation. Using twos complement notation, the leftmost bit represents the sign bit. If this bit is 1, the number is
negative; if this bit is 0 (zero), the number is positive. To convert a
negative number from binary back to decimal, complement all of the bits (1
becomes 0 and 0 becomes 1), convert that number to decimal, change the sign
of the decimal number, and then subtract 1.
In the example, where the
Imp operator is used with the two numeric values 10 and 4. In binary form (2 bytes), these two numbers appear as follows:
10: 0000000000001010
4: 0000000000000100
Using the bit-wise comparison rules from the table yields the result value
in binary form:
10: 0000000000001010
4: 0000000000000100
--------------------------
result: 1111111111110101
To determine the decimal equivalent of the result, use the twos complement
rules of conversion as follows:
Result: 1111111111110101
Complement each bit: 0000000000001010
Decimal equivalent of this binary number: 10
Opposite of this number: -10
Subtract 1 (decimal value of result): -11