Operator
# Not
forsearch
Operator
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## Description
Used to perform logical negation of a `Boolean` expression or a bitwise Not operation on an `integer` expression.
## Usage
``` xojo
result = Not expression
```
| Part | Description |
|------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| result | A `boolean` value if *expression* is a `boolean` or an `integer` value if *expression* is an `integer`. |
| expression | Any valid `boolean` or `Integer` expression. |
## Notes
The Not operator is overloaded. If you pass a `Boolean` expression, Not returns the opposite of the `Boolean` value it evaluates to. If *expression* evaluates to `True`, Not returns `False`. If *expression* evaluates to `False`, Not returns `True`.
If you pass an `integer` value, Not performs a bitwise Not operation. It inverts the bit values of the `integer` expression and sets the corresponding bit in the result according to the following table.
| Bit in Expression | Bit in Result |
|-------------------|---------------|
| 0 | 1 |
| 1 | 0 |
## Sample code
Using Not with Boolean values:
``` xojo
Var a As Boolean
Var b As Boolean
Var c As Boolean ' defaults to False
a = True
b = Not a ' b = False
b = Not c ' b = True
```
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Using Not with numeric values:
``` xojo
Var i As Integer = 255
Var result As Integer
result = Not i ' result = -256
```
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This example tests whether a `FolderItem` exists and displays a message if it doesn't.
``` xojo
Var f As FolderItem
f = FolderItem.ShowOpenFileDialog(FileTypes1.jpeg) ' defined in the File Type Set editor
If Not f.Exists Then
MessageBox("The file " + f.NativePath + "doesn't exist.")
Else ' document exists
ImageWell1.image = Picture.Open(f)
End If
Exception err As NilObjectException
MessageBox("Invalid pathname!")
```
## Compatibility
| | |
|-----------------------|-----|
| **Project Types** | All |
| **Operating Systems** | All |
`And`, `Or`, `Xor` operators; `Bitwise` class; `Operator Not` function.