Difference between revisions of "Not"
From Lazarus wiki
Jump to navigationJump to search| Line 24: | Line 24: | ||
<pascal> | <pascal> | ||
| − | function OnesComplement (const aValue:byte):byte; | + | function OnesComplement ( const aValue : byte ): byte; |
begin | begin | ||
result := Not AValue; | result := Not AValue; | ||
| Line 33: | Line 33: | ||
<pascal> | <pascal> | ||
| − | function OnesComplement2 (const aValue:shortint):shortint; | + | function OnesComplement2 ( const aValue : shortint ): shortint; |
begin | begin | ||
result := Not AValue; | result := Not AValue; | ||
| Line 48: | Line 48: | ||
* [[Byte]] | * [[Byte]] | ||
* [[Shortint]] | * [[Shortint]] | ||
| − | * [[ | + | * [[Shl#Clear_a_bit| Clear_a_bit]] (bitwise example) |
Revision as of 16:45, 12 January 2009
Boolean operation
Not produces a value of true if original value is false.
Truth table
| A | Not A |
|---|---|
| false | true |
| true | false |
Bitwise operation
Bitwise not sets the bit to 1 if corresponding bit is 0, and to 0 if bit is 1.
Ones' complement
<pascal>
function OnesComplement ( const aValue : byte ): byte; begin result := Not AValue; end;
</pascal> If you call OnesComplement(%10000000) then get %01111111 (%10000000 = 128 and %01111111 = 127). If you call OnesComplement(%00000111) then get 248 (248 = %11111000).
<pascal>
function OnesComplement2 ( const aValue : shortint ): shortint; begin result := Not AValue; end;
</pascal>
If you call OnesComplement2(%00000010) then get %11111101 (%00000010 = 2 and %11111101 = -3 when type is shortint). If you call OnesComplement2(7) then get -8 (-8 = %11111000 when type is shortint and 7 = %00000111 ).
