How To Use an Ampersand (&) to Suppress Sign Extension


Adding an ampersand (&) character to the end of a Hexadecimal number will ensure that it is not sign extended. This can be useful when an unsigned constant must be passed to a routine and the magnitude of the constant is greater than or equal to 32,768 (&H8000 in Hexadecimal). If the ampersand is not placed on the end of the constants, Visual Basic assumes that the numbers are sign extended.

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The following example illustrates the effect of an ampersand on a Hexadecimal constant:

  1. Start a new project in Visual Basic. In the default form (Form1), place the following code in the Click event for the form:

          Private Sub Form_Click()
    Dim j As Long
    j = &H8000
    Debug.Print j
    j = &H8000&
    Debug.Print j
    End Sub
  2. Run the code by pressing the F5 key. The Debug window shows the output as -32,768 followed by 32,768 indicating that the ampersand does suppress the sign.