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46 lines
1.4 KiB
Text
46 lines
1.4 KiB
Text
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'''NOT''' is a [[Boolean]] logical operator that will change a False statement to a True one and vise-versa.
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{{PageSyntax}}
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:: True = -1: False = '''NOT''' True
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* In Qbasic, True = -1 and False = 0 in boolean logic and evaluation statements.
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* NOT evaluates ONE value and returns the opposite. Yes, NOT 0 = -1 in Basic.
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* Often called a negative logic operator, it returns the opposite of a value as true or false.
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{{Template:RelationalTable}}
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{{Template:LogicalTruthTable}}
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''Example 1:'' Alternating between two conditions in a program loop.
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{{CodeStart}}
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{{Cl|DO}}
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switch = {{Cl|NOT}} switch '{{Cl|NOT}} changes value from -1 to 0 and vice-versa
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{{Cl|LOCATE}} 10, 38
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{{Cl|IF}} switch {{Cl|THEN}} {{Cl|PRINT}} "True!" {{Cl|ELSE}} {{Cl|PRINT}} "False"
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{{Cl|SLEEP}}
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k$ = {{Cl|INKEY$}}
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{{Cl|LOOP}} {{Cl|UNTIL}} k$ = {{Cl|CHR$}}(27) ' escape key quit
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{{CodeEnd}}
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''Example 2:'' Reading a file until it reaches the End Of File.
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{{CodeStart}}
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DO WHILE NOT EOF(1)
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INPUT #1, data1, data2, data3
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LOOP '' ''
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{{CodeEnd}}
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:''Explanation:'' [[EOF]] will return 0 until a file ends. NOT converts 0 to -1 so that the loop continues to run. When EOF becomes -1, NOT converts it to 0 to end the loop.
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''See also:''
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*[[DO...LOOP]], [[WHILE...WEND]],
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*[[IF...THEN]], [[AND]], [[XOR]]
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*[[OR]], [[Binary]], [[Boolean]]
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*[[Mathematical Operations]]
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{{PageNavigation}}
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