Consider the following example:
In the example given above,
we have an expression
numberOfBoysInOneClass + numberOfGirlsInOneClass * numberOfClasses
that contains two operators,
i.e., + and *.
The calculation that was supposed to happen
in the example was:
-
First, we find the sum
numberOfBoysInOneClass + numberOfGirlsInOneClass,
i.e., 50.
-
Then we multiply the above sum
with numberOfClasses i.e., 10
to get 500.
However, we got the result as 230
because the actual calculation
that was done is,
-
First, the product
numberOfGirlsInOneClass * numberOfClasses
was calculated, resulting 200.
-
Then numberOfBoysInOneClass which is 30, was
added with 200.
The calculation was done
in this order because,
when the operators + and *
are used in the same expression,
the * operator is evaluated first.
This is because * has more
precedence over +.
In the example given above,
we can use the parentheses ()
to ensure + operation is done first.
This is because ()
known as the grouping operator
has the highest precedence.
In the example given above,
we can say that (numberOfBoysInOneClass + numberOfGirlsInOneClass)
is a sub-expression inside the expression
(numberOfBoysInOneClass + numberOfGirlsInOneClass) * numberOfClasses.
Whenever there is a sub-expression wrapped in (),
the sub-expression is executed first.
Hence we get the proper output - 500, i.e.,
the product of numberOfBoysInOneClass + numberOfGirlsInOneClass
and
numberOfClasses.