{{DISPLAYTITLE:_UNSIGNED}}
[[_UNSIGNED]] defines a numerical value as being only positive.


{{PageSyntax}} 
: [[DIM]] {{Parameter|variable}} [[AS]] [{{KW|_UNSIGNED}}] {{Parameter|datatype}}

: [[_DEFINE]] {{Parameter|letterRange}} [[AS]] [{{KW|_UNSIGNED}}] {{Parameter|datatype}}


{{PageDescription}}
* Datatype can be any of the following: [[INTEGER]], [[LONG]], [[_BIT]], [[_BYTE]], [[_INTEGER64]], [[_OFFSET]]
*'''[[SINGLE]], [[DOUBLE]] and [[_FLOAT]] variable types cannot be _UNSIGNED.'''
* [[_UNSIGNED]] can be used in a [[_DEFINE]] statement to set undefined variable name first letters as all positive-only values.
* Can also be used in [[DIM]] statements or subprocedure parameter definitions following [[AS]].
* [[_UNSIGNED]] allows larger positive numerical variable value limits than signed ones.
* The unsigned variable type suffix used is the '''tilde (~)''', right before the number's own type suffix: {{Parameter|variableName~&amp;}}


&lt;center>How negative values affect the [[_UNSIGNED]] value returned by a [[_BYTE]] (8 bits). &lt;/center>
{{WhiteStart}}
                        00000001 - unsigned &amp; signed are both 1    
                        01111111 - unsigned &amp; 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}}


{{PageExamples}}
''Example 1:''  In '''QB64''', when a signed [[INTEGER]] value exceeds 32767, the value may become a negative value:
{{CodeStart}} '' ''
i% = 38000
{{Cl|PRINT}} i% '' ''
{{CodeEnd}}{{OutputStart}}-27536
{{OutputEnd}}
:''Explanation:'' Use an [[_UNSIGNED]] [[INTEGER]] or a ~% variable type suffix for only positive integer values up to 65535.


''Example 2:'' In '''QB64''', [[_UNSIGNED]] [[INTEGER]] values greater than 65535 cycle over again from zero:
{{CodeStart}} '' ''
i~% = 70000
{{Cl|PRINT}} i~% '' ''
{{CodeEnd}}{{OutputStart}} 4464
{{OutputEnd}}
:''Explanation:'' In QB64 an unsigned integer value of 65536 would be 0 with values increasing by the value minus 65536. 


''Example 3:'' 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}}(&amp;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 [[_UNSIGNED]] parts and run it again.



{{PageSeeAlso}}
* DECLARE, [[SUB]], [[FUNCTION]]
* [[DIM]], [[_DEFINE]]
* [[DEFSTR]], [[DEFLNG]], [[DEFINT]], [[DEFSNG]], [[DEFDBL]]
* [[INTEGER]], [[LONG]], [[_INTEGER64]]
* [[ABS]], [[SGN]]
* [[Variable Types]]


{{PageNavigation}}
<
