mirror of
https://github.com/QB64Official/qb64.git
synced 2024-09-28 11:17:47 +00:00
76 lines
2.5 KiB
Text
76 lines
2.5 KiB
Text
The logical [[AND]] numerical operator compares two values in respect of their bits. If both bits at a certain position in both values are set, then that bit position is set in the result.
|
|
|
|
|
|
{{PageSyntax}}
|
|
:{{Parameter|result}} = {{Parameter|firstvalue}} AND {{Parameter|secondvalue}}
|
|
|
|
|
|
{{PageDescription}}
|
|
* [[AND]] compares the bits of the {{Parameter|firstvalue}} against the bits of the {{Parameter|secondvalue}}, the result is stored in the {{Parameter|result}} variable.
|
|
* If both bits are on (1) then the result is on (1).
|
|
* All other conditions return 0 (bit is off).
|
|
* AND is often used to see if a bit is on by comparing a value to an exponent of 2.
|
|
* Can turn off a bit by subtracting the bit on value from 255 and using that value to AND a byte value.
|
|
|
|
|
|
{{Template:LogicalTruthTable}}
|
|
|
|
|
|
{{PageExamples}}
|
|
''Example 1:''
|
|
{{WhiteStart}}
|
|
101
|
|
AND
|
|
011
|
|
-----
|
|
001
|
|
{{WhiteEnd}}
|
|
|
|
:The 101 bit pattern equals 5 and the 011 bit pattern equals 3, it returns the bit pattern 001 which equals 1. Only the Least Significant Bits (LSB) match. So decimal values 5 AND 3 = 1.
|
|
|
|
|
|
''Example 2:''
|
|
{{WhiteStart}}
|
|
11111011
|
|
AND
|
|
11101111
|
|
----------
|
|
11101011
|
|
{{WhiteEnd}}
|
|
:Both bits have to be set for the resulting bit to be set. You can use the [[AND]] operator to get one byte of a two byte integer this way:
|
|
|
|
::firstbyte = twobyteint AND 255
|
|
|
|
:Since 255 is 11111111 in binary, it will represent the first byte completely when compared with AND.
|
|
|
|
:To find the second (HI) byte's decimal value of two byte [[INTEGER]]s use: secondbyte = twobyteint \ 256
|
|
|
|
|
|
''Example 3:'' Finding the binary bits on in an [[INTEGER]] value.
|
|
{{CodeStart}}
|
|
|
|
DO
|
|
{{Cl|INPUT}} "Enter Integer value from -32768 to 32767 (Enter quits): ", INTvalue&
|
|
IF INTvalue& < -32768 OR INTvalue& > 32767 OR INTval& = 0 THEN {{Cl|EXIT DO}}
|
|
{{Cl|FOR...NEXT|FOR}} exponent = 15 {{Cl|TO}} 0 {{Cl|STEP}} -1
|
|
{{Cl|IF...THEN|IF}} (INTvalue& {{Cl|AND}} 2 ^ exponent) {{Cl|THEN}} {{Cl|PRINT}} "1"; {{Cl|ELSE}} {{Cl|PRINT}} "0";
|
|
{{Cl|NEXT}}
|
|
PRINT " "
|
|
LOOP UNTIL INTvalue& = 0 'zero entry quits
|
|
|
|
{{CodeEnd}}
|
|
|
|
:Example output for 6055.
|
|
{{OutputStart}}
|
|
0001011110100111
|
|
{{OutputEnd}}
|
|
::''Note:'' The value of 32767 sets 15 bits. -1 sets all 16 bits. Negative values will all have the highest bit set. Use [[LONG]] variables for input values to prevent overflow errors.
|
|
|
|
|
|
{{PageSeeAlso}}
|
|
* [[OR]], [[XOR]], [[NOT]] {{text|(logical operators)}}
|
|
* [[AND (boolean)]]
|
|
* [[Binary]], [[Boolean]]
|
|
|
|
|
|
{{PageNavigation}}
|