Delphi Basics : Not command

DelphiBasics

Not
Keyword

Boolean Not or bitwise not of one arguments

1	keyword Not(Not Boolean expression
2	Not Integer expression

Description

The Not keyword is used in two different ways:

1. To perform a logical or boolean 'Not' of a logical value.If True, the value becomes False. If False, the value becomes True.

2. To perform a mathematical 'Not' of an integer in a bitwise fashion. The result is a bitwise 'Not' of the number - every bit value is reversed - 0 to 1 and 1 to 0.

Notes

If the boolean expression is calculated (as opposed to being a Boolean variable), then brackets are required to isolate it.

Related commands

And		Boolean and or bitwise and of two arguments
Boolean		Allows just True and False values
If		Starts a conditional expression to determine what to do next
Or		Boolean or or bitwise or of two arguments
Xor		Boolean Xor or bitwise Xor of two arguments

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Example code : Illustrate both types of Not usage

var
  num1, num2 : Word;

begin
  num1   := $2C;    // Binary value : 0000 0000 0010 1100
                    // Not'ed value : 1111 1111 1101 0011 = $FFD3

  // And used to return a Boolean value
  if Not (num1 > 0)
  then ShowMessage('num1 <= 0')
  else ShowMessage('num1 > 0');

  // And used to perform a mathematical NOT operation
  num2 := Not num1;

  // Display the result
  ShowMessage('Not $2C = $'+IntToHex(num2,2));
end;

Show full unit code

num1 > 0
Not $2C = $FFD3