QB64-PE/internal/help/_UNSIGNED.txt

{{KW|_UNSIGNED}} defines a numerical value as being positive using '''QB64''' only.


''TYPE'' {{PageSyntax}} 
::: [[DIM]] variable [[AS]] [{{KW|UNSIGNED}}] ''datatype''

::: variable [[AS]] [{{KW|_UNSIGNED}}] ''datatype''

''_DEFINE'' {{PageSyntax}}
::: {{KW|_DEFINE}} {{Parameter|LetterRange}} {{KW|AS}} [{{KW|_UNSIGNED}}] {{Parameter|datatype}}


{{PageDescription}}
* When {{KW|_UNSIGNED}} values use negative values the result subtracts from the highest value of the number's type keeping it positive.
* Datatype can be any of the following: [[INTEGER]], [[LONG]], [[_BIT]], [[_BYTE]], [[_INTEGER64]], [[_OFFSET]]
*'''[[SINGLE]], [[DOUBLE]] and [[_FLOAT]] variable types cannot be _UNSIGNED!'''
* {{KW|_UNSIGNED}} can be used in a {{KW|_DEFINE}} statement to set undefined variable name first letters as all positive only values.
* Can also be used in {{KW|DIM}} statements or Subprocedure parameter definitions following {{KW|AS}}.
* {{KW|_UNSIGNED}} allows larger positive numerical variable value limits than signed ones.
* The Unsigned variable type suffix used is the '''tilde ~''' before the number's own type suffix: variablename~&


<center>How negative values affect the {{KW|_UNSIGNED}} value returned by a {{KW|_BYTE}} (8 bits). </center>
{{WhiteStart}}
                        00000001 - unsigned & signed are both 1    
                        01111111 - unsigned & signed are both 127  
                        11111111 - unsigned is 255 but signed is -1
                        11111110 - unsigned is 254 but signed is -2
                        11111101 - unsigned is 253 but signed is -3
{{WhiteEnd}}


''Example:'' Demonstrating how _UNSIGNED variables expand the Integer range.
{{CodeStart}}

{{Cl|DIM}} n {{Cl|AS}} {{Cl|_UNSIGNED}} {{Cl|INTEGER}}
{{Cl|DIM}} pn {{Cl|AS}} {{Cl|_UNSIGNED}} {{Cl|INTEGER}}
{{Cl|LOCATE}} 3, 6: {{Cl|PRINT}} "Press Esc to exit loop"
{{Cl|FOR...NEXT|FOR}} n = 1 {{Cl|TO}} 80000
  {{Cl|_LIMIT}} 10000 ' 6.5 second loop 
  {{Cl|LOCATE}} 12, 37: {{Cl|PRINT}} n ' display current value
  {{Cl|IF...THEN|IF}} n > 0 {{Cl|THEN}} pn = n ' find highest value
  {{Cl|IF...THEN|IF}} n = 0 {{Cl|THEN}} Count = Count + 1: {{Cl|LOCATE}} 14, 37: {{Cl|PRINT}} "Count:"; Count; "Max:"; pn
  {{Cl|IF...THEN|IF}} {{Cl|INP}}(&H60) = 1 {{Cl|THEN}} {{Cl|EXIT|EXIT FOR}} ' escape key exit
{{Cl|NEXT}} n
{{Cl|END}}

{{CodeEnd}}
{{OutputStart}}

   Press Esc to exit loop




                           65462

                          Count: 13 Max: 65535


{{OutputEnd}}
''Explanation:'' The maximum value can only be 65535(32767 + 32768) so the FOR loop repeats itself. Remove the {{KW|_UNSIGNED}} parts and run it again.



{{PageSeeAlso}}
* [[DECLARE]], [[SUB]], [[FUNCTION]]
* [[DIM]], [[_DEFINE]]
* [[DEFSTR]], [[DEFLNG]], [[DEFINT]], [[DEFSNG]], [[DEFDBL]]
* [[ABS]], [[SGN]]
* [[Variable Types]]


{{PageNavigation}}