Suraku Academy | C++ Constructor & Destructor MCQs & PYQs Bank

OOP Concepts C++ Language Fundamentals Operators and Expressions Control Statements Functions and Recursion Arrays and Strings Pointers and References Classes And Objects Constructors And Destructors Inheritance In C++ Polymorphism In C++ Templates And Generic Programming STL And Standard Library File Handling Exception Handling C++ Advanced And Miscellaneous Concepts

Constructors And Destructors : Solved MCQs and PYQs

This section contains carefully selected MCQs and Previous Year Questions with explanations to help students understand concepts and prepare effectively for examinations, interviews, and competitive tests.

Topics Covered

Constructors Default Constructors Parameterized Constructors Copy Constructors Constructor Overloading Constructor Chaining Dynamic Constructors Destructors Constructor And Destructor Invocation Object Initialization Resource Management

Q: 1Which of the following is incorrect for a constructor?

It is used to initialize the state of an object

It must have the same name as that of class

It must have a return type

A class can have multiple constructors

Explanation

Option C

A constructor is a special method in object-oriented programming used to initialize the state of an object when it is created. It is automatically called when an object is instantiated.

A constructor must have the same name as the class.
It is also used to initialize object data.
A class can have multiple constructors (constructor overloading).

However, a constructor does not have any return type, not even void.

Q: 2A constructor is called whenever

An object is created

A class is created

A class is declared

More than one of the above

Explanation

Option A

A constructor is a special function inside a class that runs automatically when an object of that class is created. Its main purpose is to initialize the object data members.
A class is just a blueprint or logical design, and it does not do anything on its own. Only when an object is created from that class does memory get allocated, and at that moment, the constructor is automatically called to set initial values.

Q: 3A constructor which takes reference is called.

Default constructor

Dummy constructor

Copy constructor

Reference constructor

Explanation

Option C

A copy constructor is a special constructor that is used to create a new object using an existing object. It takes a reference to an object of the same class as its parameter.
Syntax:
ClassName(ClassName &obj)
{
// copy data members
}

Q: 4Consider the below code (read very carefully)
class myclass
{
int a,b;
public:
void setData(int p)
{
a=b=p;
}
};
void main()
{
myclass m1,m2;
m1.setData(10);
m2=m1;
myclass m3=m1;
}
What happen when the statement myclass m3=m1; is executes:

Executes implicit assignment overloaded function and copy member of m1 to m3.

Executes copy constructor and copy member of m1 to m3.

Executes default constructor and no members are copied.

Error occurred because we cannot copy one object member to another.

Explanation

Option B

In C++, when an object is created and initialized using another object of the same class, the copy constructor is called.
In statement myclass m3=m1;

The m3 is being created and initialized using the existing object m1.
This is not assignment. It is initialization at the time of object creation. Therefore, the copy constructor of myclass is executed.

Since no user-defined copy constructor is provided, the compiler generates a default copy constructor, which performs a member-wise copy of a and b from m1 to m3.

Q: 5Which of the following is a valid constructor declaration for the class Book?

public String Book()

public float Book()

protected String Book()

public Book()

Explanation

Option D

In Object-Oriented Programming, a constructor is a special method used to initialize objects.

The constructor name must be exactly the same as the class name.
It does not have any return type not even void.
It can have access modifiers like public, private, or protected.

Q: 6Which of the following statements about destructors in C++ is TRUE?

A destructor must have a return type, typically void.

A destructor can take parameters to customize object cleanup.

If a class does not define a destructor, the compiler provides a default public destructor.

Destructors can be overloaded if needed.

Explanation

Option C

If you do not write a destructor, the compiler generates a default destructor, which is public and empty.
A destructor is a special member function of a class that is automatically called when an object goes out of scope or is deleted using delete. The purpose of destructor is to clean up resources (like memory, file handles, network connections, etc.) that the object was using.
Generally, a custom destructor is required when a class allocates memory using the new operator, opens files or databases, or acquires other system resources. In such cases, it is necessary to release these resources. If they are not released properly, it can lead to memory leaks or resource leaks, which may cause the program to slow down or crash.

Q: 7The _______ is a guaranteed function which executes when object of class is created.

Static function

Constructor function

Inline function

Default function

Explanation

Option B

In C++, a constructor is a special member function of a class that is automatically and guaranteed to execute whenever an object of that class is created.

The constructor has the same name as the class.
It is used to initialize data members of the object.
It does not have a return type, not even void.

Q: 8In C++, a constructor without any argument is called a

Copy Constructor

Parameterized Constructor

Default Constructor

None of the above

Explanation

Option C

In C++, a constructor is a special member function used to initialize objects. When a constructor is defined without any arguments or parameters, it is called a Default Constructor.
class Demo
{
public:
Demo()
{
cout<<"Object Created Successfully";
}
};

Q: 9

Consider the program below. What will be the output?

#include<iostream>
#include<string>
using namespace std;
class Sample {
   string name;
   public:
   Sample() {
      cout<<”s”<<” ”;
   }
   Sample (string s) : name (s) {
      cout<<name<<” ”;
   }
};
int main() {
   Sample s1;
   Sample *s2=new Sample (“s2”);
   Sample *s3;
   new Sample (“s4”);
   return 0;
}

s s2 s s4

s2 s s4

s s2 s4

s2 s4 s

Explanation

Option C

The line Sample (string s) : name (s), is a parameterized constructor of the class Sample, and : name(s) is an example of a member initializer list in C++. It means that the data member name will be initialized with the value of s before the constructor body runs.

Q: 10Which of the following statements is/are wrong about constructor in object-oriented programming?
1. The name of the constructor is same as class name.
2. It can have a return value.
3. Constructor is the first code invoked when an object is created.
4. Constructor name need not be the same as that of class name.

Only 2

Only 3

2 and 4

2,3 and 4

Explanation

Option C

A constructor is a special member function of a class that is executed automatically when an object of the class is created. It is mainly used to initialize instance variables.

Constructor name must match class name.
Constructor has no return type, not even void.
Constructor called automatically when object is created.
Constructor function is used for initialization.
Constructor can be overloaded.

Showing 10 / 13 Questions

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Constructors And Destructors : MCQs & PYQs with Explanation

Constructors And Destructors : Solved MCQs and PYQs

Topics Covered

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