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&&
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Logical AND.
Returns 1 whenever both of its operands are true; otherwise, returns 0. Non-zero numerical values, non-null strings, and non-null heap variables (pointers and object references) are considered true, everything else is false.
Operands must be scalars or single-element arrays. The && operator short-circuits; the second operand will not be evaluated if the first is false.
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PRINT, 5 && 7
IDL Prints: 1
PRINT, 5 && 2
IDL Prints: 1
PRINT, 4 && 0
IDL Prints: 0
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||
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Logical OR.
Returns 1 whenever either of its operands are true; otherwise, returns 0. Uses the same test for "truth" as the && operator.
Operands must be scalars or single-element arrays. The || operator short-circuits; the second operand will not be evaluated if the first is true.
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IF ((5 GT 3) || (4 GT 5)) THEN $
PRINT, 'True'
IDL Prints:
True
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~
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Logical negation.
Returns 1 when its operand is false; otherwise, returns 0.
Uses the same test for "truth" as the && operator.
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PRINT, ~ [1, 2, 0]
IDL Prints:
0 0 1
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