Decision Making
13. Boolean Expressions
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Boolean Expressions
Relational Operators |
|
|---|---|
Operator |
Meaning |
A == B |
is A equal to B ? |
A < B |
is A less than B ? |
A <= B |
is A less than or equal to B ? |
A > B |
is A Greater than B ? |
A >= B |
is A Greater than or equal to B ? |
A != B |
is A not equal to B ? |
We need to look at the condition part of the if statement. Usually this is a boolean expression. Recall that an expression is is a combination of literals, operators, variable
names, and parentheses used to calculate a value.
Boolean expressions often compare numbers. A relational operator says how the numbers are compared.
Here are some annoying details (that will be really annoying later on if you forget about them):
- The operator for "equal" is
==(two equal signs in a row). In your web browser it may be hard to see that there are two equal signs. - The operator for "not equal" is
!=(exclamation point equal sign).
It is easy to forget these two details, and easy to overlook these details in a program. You might spend hours debugging a program because a = was used where a == belongs.
Question 13: