Lesson 3.1

• Header files in C++

  • iostream: Contains definitions of objects like cin, cout, cerr, etc.
  • iomanip: Contains methods for manipulating streams like setw, setprecision
  • fstream: Describes file stream handling
  • bits/stdc++: Includes every standard library, used for time-sensitive tasks
• Pointers

  • int *ptr;
  • ptr = arr;
• Array Index


  Each element in an array is associated with a number
• C++ Array Initialization

  1. int x[6] = {19, 10, 8, 17, 9, 15};

  2. int x[] = {19, 10, 8, 17, 9, 15};

  3. int x[6] = {19, 10, 8};
• References in C++

  • References serve as aliases for existing variables
  • A reference acts as a nickname for another variable, creating a direct binding to its memory location
  • Changes made to a reference directly affect the original variable they refer to
  • References cannot be reassigned to point to different variables after
• C++ Array Declaration

  dataType arrayName[arraySize];
• C++ Array Declaration

  • int x[6];
• Arrays in C++


  • Arrays are a fundamental data structure in C++ used to store collections of elements of the same data type
  • Arrays store multiple values of the same data type in contiguous memory locations
  • Individual elements are accessed using an index, starting from 0
  • The size of an array is determined at declaration and cannot be changed later
• Pointers in C++

  • Pointers are variables that hold addresses of other variables
  • Pointers can store the address of cells of an array
• Declaring a Reference

  • data_type: The data type of the existing variable
  • reference_name: The chosen name for your reference
  • existing_variable_name: The variable you want to create a reference to
• PROGRAMMING SAMPLE 2 (references)


  #include <iostream>

  using namespace std;

  int main () {

  int i;

  double d;

  int& r = i;

  double& s = d;

  i = 5;

  cout << "Value of i : " << i << endl;

  cout << "Value of i reference : " << r << endl;

  d = 11.7;

  cout << "Value of d : " << d << endl;

  cout << "Value of d reference : " << s << endl;

  return 0;

  }
• Reference


  • A reference acts as a nickname for another variable, creating a direct binding to its memory location
  • Changes made to a reference directly affect the original variable they refer to
  • References cannot be reassigned to point to different variables after initialization
• PROGRAMMING SAMPLE 2 (references) Output

  • Value of i : 5, Value of i reference : 5, Value of d : 11.7, Value of d reference : 11.7
• PROGRAMMING SAMPLE 1 (array and pointer)

  // C++ Program to display address of each element of an array

  #include <iostream>

  using namespace std;

  int main()

  {

  float arr[3];

  float *ptr;

  cout << "Displaying address using arrays: " << endl;

  for (int i = 0; i < 3; ++i)

  {

  cout << "&arr[" << i << "] = " << &arr[i] << endl;

  }

  ptr = arr;

  cout<<"\nDisplaying address using pointers: "<< endl;

  for (int i = 0; i < 3; ++i)

  {

  cout << "ptr + " << i << " = "<< ptr + i << endl;

  }

  return 0;

  }
• PROGRAMMING SAMPLE 1 (array and pointer) Output

  • Displaying address using arrays: &arr[0] = 0x61fef0, &arr[1] = 0x61fef4, &arr[2] = 0x61fef8

  Displaying address using pointers: ptr + 0 = 0x61fef0, ptr + 1 = 0x61fef4, ptr + 2 = 0x61fef8
• Declaring a Reference

  data_type &reference_name = existing_variable_name