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The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

  ◄Expressions and Operators►   ◄Logical Operators►   ◄Contents►   ◄Index►
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Logical Operators
 
Logical operators perform tests on multiple relations, bit manipulations, or
Boolean operations and return a true (nonzero) or false (zero) value to be
used in making a decision.
 
Examples
 
  IF D < 200 AND F < 4 THEN 80
  WHILE I > 10 OR K < 0
  .
  .
  .
  WEND
  IF NOT P THEN PRINT "Name not found"
 
The six logical operators in BASIC, listed in order of precedence, are:
 
  Operator              Meaning
  NOT                   Logical complement
  AND                   Conjunction
  OR                    Disjunction (inclusive "or")
  XOR                   Exclusive "or"
  EQV                   Equivalence
  IMP                   Implication
 
Each operator returns results as indicated below. A "T" indicates a true
value and an "F" indicates a false value. Operators are listed in order of
operator precedence.
 
 
Values of      Value Returned by Logical Operator
                      X    X    X     X     X
                NOT  AND  OR   XOR   EQV   IMP
X     Y          X    Y    Y    Y     Y     Y
─────────────────────────────────────────────────
T     T          F    T    T    F     T     T
 
T     F          F    F    T    T     F     F
 
F     T          T    F    T    T     F     T
 
F     F          T    F    F    F     T     T
 
In an expression, logical operations (also known as Boolean operations) are
performed after arithmetic and relational operations. The operands of
logical operators must be in the range -2,147,483,648 to +2,147,483,647.
Operands are converted to integers (or, if necessary, long integers) before
the logical operation is done. (If the operands are not in this range, an
error results.) If the operands are either 0 or -1, logical operators
return 0 or -1 as the result.