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09review (ObjectsAndClasses)

This document discusses object-oriented programming concepts like classes, objects, constructors, encapsulation, and accessor/mutator functions. It provides examples of declaring Circle objects using no-arg and parameterized constructors, and explains that data fields should be private and accessed/modified through public accessor/mutator functions to encapsulate data.

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19 views3 pages

09review (ObjectsAndClasses)

This document discusses object-oriented programming concepts like classes, objects, constructors, encapsulation, and accessor/mutator functions. It provides examples of declaring Circle objects using no-arg and parameterized constructors, and explains that data fields should be private and accessed/modified through public accessor/mutator functions to encapsulate data.

Uploaded by

cse12005006brur
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOC, PDF, TXT or read online on Scribd
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Chapter 9 Objects and Classes

1. See the section "Defining Classes for Objects."

2. Constructors are special kinds of functions that are


called when creating an object. Constructors do not
have a return type—not even void.

3. To declare an object using the no-arg constructor, use


ClassName objectName;

To declare an object using the constructor with


arguments, use ClassName objectName(arguments);

4. Once an object name is declared, it cannot be


reassigned to reference another object. Object names
are like constants.
5. 6 6

6. (a) Line 3 is wrong. It should be

Circle c1;

(b) Line 4 is wrong. The object cannot be declared


again.

7. A data field cannot be initialized when it is declared


in C++.

8. The first statement declares an object of Circle. The


object is created using the Circle’s no-arg
constructor.

The second statement is incorrect.

9. The first statement declares an object of Circle. The


object is created using the Circle’s no-arg
constructor.

For the second statement, the left-hand side of the =


sign does the same as the first statement and the
right-hand side creates an anonymous object using the
Circle’s no-arg constructor and copies the object to c.
10. Declare all data fields, constructors, and function
prototypes in the interface and implement functions in
a separate file.

11. (a) output is 5


(b) Output is 8

12. If your program include two header files and one of


which actually include the other, then your program
will receive the multiple declaration error. To prevent
it, use the #ifndef directive.

13. The #define directive defines a constant.


14.
Implement all the functions in the header file.
class Circle

public:

Circle()

radius = 1;

};

Circle(double newRadius)

radius = newRadius;

double getArea()

return radius * radius * 3.14159;

};

double getRadius()

return radius;

};

void setRadius(double newRadius)

radius = newRadius;

};
private:

double radius;

};

15.

You cannot use c.radius, since radius is a private data field.

16. Accessor function is for retrieving private data value and


mutator function is for changing private data value. The naming
convention for accessor function is getDataFieldName() for non-
boolean values and isDataFieldName() for bool values. The naming
convention for mutator function is setDataFieldName(value).

17. Two benefits: (1) for protecting data and (2) for easy
to maintain the class.

18. Yes.

17.
100000
?
Explanation: Loan’s no-arg constructor is used to initialize loan, but i is not
initialized.

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