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Conditions

We have seen relational comparisons used for tests.

may want to combine several relational comparisons into a more complex test

use Boolean (logical) operators for this:

There are several ways to write equivalent conditions, using and, or, xor, not, and the relational operators. Take care to write conditions as clearly as possible

NOT

NOT (TRUE)	FALSE
NOT (FALSE)	TRUE

Example:

	not (age <= 21)

AND

FALSE

and

FALSE

and

TRUE

FALSE

TRUE

and

FALSE

TRUE

and

TRUE

Examples:

	(age >= 21) and (age <= 65)
	(age >  20) and (age <  66)
	(sex = 'M') and (age >= 18)

OR

FALSE

TRUE

FALSE

TRUE

Examples:

	(age < 18) or (sex = 'F')

	not ( (age >= 18) and (sex = 'M') )

	((age >= 60) and (sex = 'F')) or ((age >= 65) and (sex = 'M'))

XOR (Exclusive OR)

FALSE

xor

FALSE

xor

TRUE

xor

FALSE

TRUE

xor

TRUE

FALSE

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c-lokan@adfa.oz.au / 13 Feb 96