GATE-CS-2016 (Set 1) - Chapter 32

Introduction

GATE-CS-2016 (Set 1) - Chapter 32 is a part of the GATE 2016 (Computer Science and Information Technology) exam. This section focuses on programming concepts in C and C++ languages. The questions in this chapter test the candidate's understanding of basic programming concepts, data structures, algorithms, and problem-solving skills.

Syllabus

The syllabus of GATE-CS-2016 (Set 1) - Chapter 32 includes the following topics:

1. Pointers and arrays
2. Storage classes
3. Functions and parameter passing
4. Recursion
5. Structures and unions
6. Typedef
7. File handling
8. Standard C library functions

Sample Questions

Question 1

#include <stdio.h>
#include <stdlib.h>

int *fun(int *p)
{
  p++;
  return p;
}

int main()
{
  int a[5] = {10, 20, 30, 40, 50};
  int *ptr = a;

  ptr = fun(ptr);
  printf("%d ", *ptr++);

  ptr = fun(ptr);
  printf("%d ", *ptr);

  return 0;
}

Output: 30 40

Explanation: The function fun receives a pointer to an integer and increments it by one. The main function initializes an integer array a and a pointer ptr to the start of a. Then, ptr is passed to fun function, where it is incremented by one. The returned value of fun is stored in ptr. The value of ptr is now pointing to the element at index 1 in a, which has the value 20.

After that, ptr is again passed to fun function, where it is again incremented by one. Now, ptr is pointing to the element at index 2 in a, which has the value 30. The first printf statement prints the value pointed by ptr (which is 30), and the second printf statement prints the value pointed by ptr (which is 40).

Question 2

#include <iostream>
using namespace std;

class A
{
public:
  int a;
  A() { a = 10; }
  void display() { cout<<a<<endl; }
};

class B: public A
{
public:
  int b;
  B() { b = 20; }
  void display() { cout<<a<<" "<<b<<endl; }
};

int main()
{
  A *ptr = new B();
  ptr->display();
  delete ptr;
  return 0;
}

Output: 10

Explanation: This program creates two classes, A and B. B is derived from A using public inheritance. A has a public integer member variable a, and a constructor that initializes a to 10. B has a public integer member variable b, and a constructor that initializes b to 20.

The main function creates a pointer ptr of class A type and assigns it the address of a dynamically created object of class B type. The display function of class B is overridden to print both a and b variables of the object. However, the display function of class A is not overridden.

When a member function is called from a pointer to an object of a derived class using a pointer of its base class type, then the function of the base class is called if it is not overridden. In this case, ptr is of A type, so ptr->display() calls the display function of class A, which only prints the value of a (10).