Logical Operators

1. Logical Operators

2. Code
Code:
 Using logical operators:
 if (condition or condition)
Statement
 if (condition and condition)
Statement

3. The logical ‘or’ And ‘and’ Operators

4. Logical Operators
A third logical operator is not.
The not command basically evaluates the
opposite of the statement
It can be used to simplify possible
outcomes. Instead of listing all the options
you can list the 1 it can’t be
Ex. Rolling an even number, passwords,
etc.
 if not (name) == “Jason”
This reads if the name is not Jason then…

5. Code
 Using ‘not’ operator:
 if not (condition)
Statement
 ‘not’ has the highest precedence, followed by ‘and’,
then ‘or’
 If the value of an expression can be determined by
evaluating just the sub-expression on left side of a
logical operator, then the sub-expression on the right
side will not be evaluated (short circuit evaluation)

6. The logical ‘not’ Operator

7. Example: Logical Operators
x = 12
y = 5
z = -4
(x > y) && (y > z)
(x > y) && (z > y)
(x <= z) || (y == z)
(x <= z) || (y != z)
!(x >= z)

8. Validating User Input
 Input validation: inspecting input data to determine
whether it is acceptable
 Bad output will be produced from bad input or not
utilized at all.
 “Crap in, crap out”
 Can perform various tests:
 Range
 Reasonableness
 Valid menu choice
 Divide by zero

9. Input Validation