Question 1

How are C# and C++ different with regard to compilation, garbage collection, access specifiers, test variables, and binaries?

Accepted Answer

Feature 
 C# 
 C++

Compilation  
 C# code is converted into intermediate language code after compilation.  
 C++ code is converted into machine code directly after compilation.

Garbage collection 
 C# supports garbage collection 
 C++ does not support garbage collection.

Access specifiers   
 They are public, private, protected, internal & protected internal.   
 They are public, private, protected.

Test variables   
 The test variable can be a string in switch statement.   
 The test variable cannot be a string in switch statement.

Binaries   
 The size of binaries is high because of overhead libraries.   
 The size of binaries is low and lightweight.

Question 2

What are the various OOP concepts in C++?

Accepted Answer

Classes: It is a user-defined datatype  
 Objects: It is an instance of a class  
 Abstraction: It is a technique to show only necessary details  
 Encapsulation: It helps wrapping of data in a single unit  
 Inheritance: It is the capability of a class to derive properties and characteristics from another class 
 Polymorphism: Polymorphism refers to many forms of the same thing

Question 3

What are the different data types present in C++?

Accepted Answer

The four data types in C++ are:

Primitive: char, short, int, float, long, double, bool, etc.  
 Derived: array, pointer, etc.  
 Enumeration: enum  
 User-defined data types: structure, class, etc.

Question 4

What are the C++ access specifiers?

Accepted Answer

Public: They allow access to all data members and member functions outside the class.  
 Protected: They allow access to all data members and member functions inside the class and to the derived class.  
 Private: They don’t allow access to data members and member functions outside the class.

Question 5

What is operator overloading?

Accepted Answer

It is an important element for performing operations on user-defined data types. Operator overloading allows you to modify the default meaning to the operators like +, -, *, /, and

class complex{

private:

float r, i;

public:

complex(float r, float i){

this->r=r;

this->i=i;

}

complex(){}

void displaydata(){

cout

Question 6

What are classes and objects in C++?

Accepted Answer

User-defined data types with member functions and data members customized according to demands and requirements are classes. A class can be accessed with the help of an object. A keyword class is used to declare a user-defined data type.

An object is a data type that is a class and an entity with value and state. Objects are used as catalysts or to represent a class member and may contain different parameters or none.

Question 7

Define token in C++.

Accepted Answer

The smallest individual element of a program that is understood by a compiler is a token. A token has:   
 
 Keywords that have a special meaning to the compiler.  
 Identifiers that hold a unique value/identity.   
 Constants that never change their value throughout the program   
 Strings that contain the homogenous sequence of data   
 Special Symbols that have special meaning and cannot be used for another purpose  
 Operators that perform operations on the operand

Question 8

What is a copy constructor?

Accepted Answer

It is a member function that initializes an object using another object of the same class. A copy constructor takes a reference to an object of the same class as an argument. Example:

class Class_name

{

public:

Class_name()

{

cout

Question 9

What is the difference between virtual functions and pure virtual functions?

Accepted Answer

A member function in the base class that is redefined in a derived class is a virtual function. It is declared using the virtual keyword.

class base{

public:

virtual void fun(){

}

};

A function that has no implementation or body and is declared by assigning 0 is a pure virtual function. 
 
Example  
  class base{

public:

virtual void fun()=0;

};

Question 10

Give an example of this pointer in C++.

Accepted Answer

class A{

private:

int value;

public:

void setvalue(int x){

this->value=x;

}

};

int main(){

A a;

a.setvalue(5);

return 0;

}

Question 11

What is the difference between structure and class?

Accepted Answer

Structure  
 Class

Members of the structure are public by default.  
 Members of the class are private by default.

Default access specifiers for base class/struct are public when deriving a struct from a class/struct.  
 When deriving a class, default access specifiers are private.

Question 12

How do you allocate and deallocate memory in C++?

Accepted Answer

To allocate memory, we use the new operator. To deallocate memory, we use the deletes operator in C++.  
Example

int value=new int;  		//allocates memory for storing 1 integer 
delete value;          		// deallocates memory taken by value 
 
int *arr=new int[10];    	//allocates memory for storing 10 int 
delete []arr;              	// deallocates memory occupied by arr

Question 13

What will the value of x be in the following C++ program?

Accepted Answer

#include

using namespace std;

int main(){

int a=1;

int x=(a++)++;

cout 
   
The value will lead to a compile time error. The expression (a++)++ is invalid in C++. The postfix increment operator a++ returns a temporary value, and you cannot apply the increment operator (++) to a temporary value. This leads to a compilation error.

Question 14

What will be the output of this C++ program?

Accepted Answer

#include

using namespace std;

class A{

public:

virtual void a()=0;

A(){

cout

The output of the given program will be a compile time error. In C++, when a class contains a pure virtual function, it becomes an abstract class, and you cannot create an object of an abstract class directly. In this case, class A has a pure virtual function a(), making it an abstract class. When you try to create an object of class B in the main function, which is derived from A, it leads to a compilation error.

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Feature	C#	C++
Compilation	C# code is converted into intermediate language code after compilation.	C++ code is converted into machine code directly after compilation.
Garbage collection	C# supports garbage collection	C++ does not support garbage collection.
Access specifiers	They are public, private, protected, internal & protected internal.	They are public, private, protected.
Test variables	The test variable can be a string in switch statement.	The test variable cannot be a string in switch statement.
Binaries	The size of binaries is high because of overhead libraries.	The size of binaries is low and lightweight.