1. What are the main types of operators in terms of number of arguments?

Operators are classified based on the number of operands they require.

1. Unary Operator
   • Takes one operand
   • Example: ++a, --a
2. Binary Operator
   • Takes two operands
   • Example: a + b, a * b
3. Ternary Operator
   • Takes three operands
   • Example: condition ? value1 : value2

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2. What is the “this” pointer?

The this pointer is a special pointer available inside member functions that points to the current object of the class.

Example

class Test{

int x;

public:

void setX(int x){

this->x = x;

}

};

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3. What are manipulators?

Manipulators are special functions used with input/output streams to format data.

Example

endl

setw()

setprecision()

Example:

cout << setw(10) << 100;

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4. If requested memory is not available what do malloc/calloc/new return?

• malloc / calloc → return NULL
• new → throws bad_alloc exception (or returns NULL in older compilers)

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5. What is memory leak?

A memory leak occurs when dynamically allocated memory is not released using delete or free, causing memory wastage.

Example:

int *p = new int;

If delete p; is not used → memory leak occurs.

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6. What does code optimization mean?

Code optimization means improving program efficiency without changing output.

Goals:

• Reduce execution time
• Reduce memory usage
• Improve performance

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7. Difference between structure and class

Structure	Class
Members are public by default	Members are private by default
Mostly used for simple data	Used for full OOP programming

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8. Difference between endl and \n

endl	\n
Inserts new line and flushes buffer	Only inserts new line
Slower	Faster

Example:

cout << "Hello" << endl;

cout << "Hello\n";

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9. When does an object get destroyed?

An object is destroyed when:

• It goes out of scope
• Program ends
• delete is called for dynamic object

At that time destructor is executed.

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10. What is static variable and its lifetime?

A static variable is initialized only once and retains its value between function calls.

Lifetime = entire program execution

Example

void func(){

static int x = 0;

x++;

}

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11. Output of the following functions

Function 1

void func1(){

int x = 0;

x++;

cout << x << endl;

}

Output if called 3 times

1

1

1

Because x is created again every time.

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Function 2

void func2(){

static int x = 0;

x++;

cout << x << endl;

}

Output

1

2

3

Because static variable retains value.

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12. What is friendship in classes?

A friend function can access private and protected members of a class.

Example

class A{

private:

int x;

friend void show(A);

};

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13. Limitations of friendship

1. Friendship is not inherited
2. Friendship is not mutual
3. Friendship is not transitive

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14. What are disadvantages of templates?

1. Code becomes difficult to read
2. Compiler errors become complex
3. Debugging becomes harder

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15. What is assignment operator?

The assignment operator (=) is used to assign the value of one object to another.

Example

a = b;

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16. Constructor and Destructor call order

If object of class A is inside class B

class B{

A obj;

};

Constructor order

1. A constructor
2. B constructor

Destructor order

1. B destructor
2. A destructor

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17. Unary vs Binary operator

Unary Operator	Binary Operator
Works on one operand	Works on two operands
Example: ++a	Example: a + b

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Overloading Syntax

return_type operator symbol(parameters);

Example

Vector operator+(Vector v);

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18. What are steps to design a good program?

1. Problem analysis
2. Algorithm design
3. Coding
4. Testing
5. Debugging
6. Documentation

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19. What is truth table?

A truth table shows the output of a logical expression for all possible combinations of inputs.

Example

A	B	A AND B
0	0	0
0	1	0
1	0	0
1	1	1

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20. What is default constructor?

A constructor without parameters is called a default constructor.

Example

class A{

public:

A(){

cout<<"Default Constructor";

}

};

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21. What is conversion constructor?

A constructor that converts one data type into class type.

Example

class Test{

int x;

public:

Test(int a){

x = a;

}

};

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22. Why are utility functions kept private?

Utility functions are kept private so they:

• cannot be accessed outside the class
• are used only internally
• improve security

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23. What does free format language mean?

C and C++ are free format languages, meaning:

• spaces
• tabs
• line breaks

do not affect program logic.

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24. Types of user defined conversions

1. Conversion Constructor
2. Operator Conversion Function

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25. What is STL?

STL = Standard Template Library

Provides ready-made:

• containers (vector, list)
• algorithms
• iterators

Advantages:

• Code reuse
• Efficiency
• Type safety