Logical Conditions-Relational Operators:
A logical condition is an expression formed by some variables and some relational, equality and logical operators. A simple example is:
height > width
Here height and width are two variables, and > is the relational operator "greater than". The value of a logical condition is either true ( binary value 1) or false ( binary value 0). The various relational and equality operators are given in the table below:
|
Operator
|
Meaning
|
|
<
|
less
than
|
|
<=
|
less
than or equal to
|
|
>
|
greater
than
|
|
>=
|
greater
than or equal to
|
|
=
=
|
equal
to
|
|
!=
|
not
equal to
|
More complicated conditions can be build by using arithmetic expressions of variables on the left and the right of relational and equality operators:
Example: 1.08 * height + 3.5 * pow( width, 3) >= 7.8 + width * height
Even more complicated conditions can be build by using the logical
operators given in the table below to connect more than one conditions
:
|
Operator
|
Meaning
|
|
&&
|
and
|
|
||
|
or
|
|
!
|
not
|
The resulting composite condition may look like this:
Example: height > 3.4 && height < 5.6
This condition will have the value true if height is between 3.4 and 5.6, but it will have the value false if height is say 7.4 or 2.5 or even 3.4 or 5.6.
When
you need to write more complicated conditions, use parentheses.
