Logical negation: !, not

The logical negation operator is used to determine the oposite value. in our case: if input is true then output is false, and if input is false the result is true. In next table you can find all possibilities:

a	x
False	True
True	False

information about the table: a is input, x is result

!

Description

! par1

Used keywords: !

Input

par1 - Logical value

Output

Result - Logical value

Compatible programing languages:
C | Visual C++ .NET | C++ | C# | Java | JavaScript | PHP

Examples

Example

In the source code you can find the equivalent of the above table, for easier orientation at the end of each line is a comment which shows the result.

a1 = !false; // a1 = true
a2 = !true; // a2 = false

Example

Even one example in what situations we can use the operation logical negation:

!a
!b && true
!(10 >a || a<5)

Example

Other pieces of example codes:

!a

not

Description

not par1

Used keywords: not

Input

par1 - Logical value

Output

Result - Logical value

Compatible programing languages:
FreeBASIC | Visual Basic .NET | Pascal | Free Pascal | Object Pascal

Examples

Object Pascal

In the source code you can find the equivalent of the above table, for easier orientation at the end of each line is a comment which shows the result.

a1 := not false; // a1 = true
a2 := not true; // a2 = false

Object Pascal

Even one example in what situations we can use the operation logical negation:

not a
not b and true
not(10 >a or a<5)

Object Pascal

Other pieces of example codes:

repeat
  inc(i);
  if i=5 then
    break;
until not i <10;

not a

repeat dec(i) until not i > 0;

You can find it in the following collections: logical operators

Logical negation in another programming language: