ITPEC FE Subject B October 2025 Question 6

Topic: OOP & Inheritance

From the answer group below, select the correct answer to be inserted into blank in the description.

Class Rectangle represents a two-dimensional figure, and class Cuboid represents a three-dimensional figure. The class Cuboid is a subclass of the class Rectangle. Figures 1 and 2 explain the classes Rectangle and Cuboid, respectively.

Member variableTypeDescription
lengthintegerDimension of length.
widthintegerDimension of width.
ConstructorDescription
Rectangle(integer: _length,integer: _width)Initialize member variable length with _length and member variable width with _width.
MethodReturn valueDescription
enlarge(Rectangle:shape)NoneTo increase the size, add shape.length to length and shape.width to width.
output()NoneOutput in format “(length, width)”.

Figure 1 Class Rectangle

Member variableTypeDescription
heightintegerDimension of height.
ConstructorDescription
Cuboid(integer: _length,integer: _width,integer: _height)Constructor of the super class is called with _length and _width as arguments in that order, and member variable height is initialized with the argument _height.
MethodReturn valueDescription
enlarge(Cuboid:shape)NoneTo increase the size, add shape.length to length, shape.width to width and shape.height to height.
output()NoneOutput in format “(length, width, height)”.

Figure 2 Class Cuboid

When the program is executed, it is expected to produce the output “blank”.

[Program]
Rectangle: f1 ← Rectangle(5, 2)
Cuboid: f2 ← Cuboid(9, 4, 7)
f1.enlarge(f2)
f1.output()

Answer group

Explanation

(14, 6) — f1 is a Rectangle, so its enlarge and output are the Rectangle versions, which know only length and width.

  • •f1 ← Rectangle(5, 2): length 5, width 2
  • •f2 ← Cuboid(9, 4, 7): calls Rectangle(9, 4), then sets height to 7
  • •f1.enlarge(f2): f1 is a Rectangle, so enlarge(Rectangle: shape) runs. A Cuboid is a Rectangle, so f2 is a valid argument, and the method adds only shape.length and shape.width: length becomes 5 + 9 = 14, width becomes 2 + 4 = 6
  • •f1.output(): the Rectangle format, two values, (14, 6)

f2.height is never read, and f1 has no height to change.

Answer (e)

Why not others:

  • •(a) (5, 2) — ignores f1.enlarge(f2), which changes f1
  • •(b) (5, 2, 7) — ignores the enlargement and gives f1 a third value that a Rectangle does not have
  • •(c) (9, 4) — treats enlarge as copying the dimensions of f2 instead of adding them
  • •(d) (9, 4, 7) — prints the initial state of f2, not f1
  • •(f) (14, 6, 7) — adds correctly but then prints as a Cuboid; f1 is a Rectangle, whose output has only length and width

Key rule: The object a method is called on decides which class's method runs; a subclass instance passed as a superclass argument is used only through the superclass's members.

OOP & Inheritance · AI-written, may contain errors

Practice this exam

This question comes from an official ITPEC past paper. ITPEC Practice is an independent study tool and is not affiliated with ITPEC. See the official FE past-paper collection or Report an issue.