Basic Questions On Array

Inserting Elements into an Array

Data structure questions with story like explanation.

Are you learning C++ or Java and struggling with inserting elements into an array? If so, this blog post is for you! In this post, we'll walk through a program that inserts a new value into an array at a specified index.

For example:
If we have an array {1, 2, 3, 4, 5} and we want to insert the value 6 at index 2, the resulting array would be {1, 2, 6, 3, 4, 5}. Please make sure to ask the user for the index and value to be inserted.

Before we jump into the solution, let's take a moment to understand the logic:

Imagine a classroom with 5 desks, where each desk represents an element in an array. Each desk has a student sitting on it and the desks are numbered from 1 to 5.

Now let's say the teacher wants to add a new student to the classroom and wants to place them in the third desk. To do this, they would have to move the student on the third desk to the fourth desk, the student on the fourth desk to the fifth desk, and finally, they can place the new student on the third desk.

In the same way, when we want to insert an element into an array, we need to shift all the elements to the right of the insertion point to create space for the new element. Once we have created space, we can insert the new element into the array.

For example:
If we have an array {1, 2, 3, 4, 5} and we want to insert the value 6 at index 2, we would shift the values 3, 4, and 5 one position to the right and then insert 6 at index 2. The resulting array would be {1, 2, 6, 3, 4, 5}.

First, let's take a look at the program code: Java

import java.util.*;

      public class Main {
          public static void Insert(int index, int val) {
              int[] A = {1, 2, 3, 4, 5};
              int len = A.length;
              if (index >= 0 && index < len) {
                  for (int i = len; i > index; i--) {
                      A[i] = A[i - 1];
                  }
                  A[index] = val;
                  len++;
              }
              System.out.print("After updating Array: ");
              for (int i = 0; i < len; i++) {
                  System.out.print(A[i] + " ");
              }
          }
      
          public static void main(String[] args) {
              Scanner sc = new Scanner(System.in);
              int a, b;
              System.out.println("Enter the Index no.");
              a = sc.nextInt();
              System.out.println("Enter the value that you want to enter:");
              b = sc.nextInt();
      
              Insert(a, b);
          }
      }

C++ code:

  #include <iostream>
  using namespace std;
  
  void Insert(int index, int val)
  {
    int A[] = {1, 2, 3, 4, 5};
    int len = sizeof(A) / sizeof(A[0]);
    if (index >= 0 && index < len)
    {
      for (int i = len; i > index; i--)
      {
        A[i] = A[i - 1];
      }
      A[index] = val;
      len++;
    }
    cout << "After updating Array :";
    for (int i = 0; i < len; i++)
    {
      cout << A[i] << " ";
    }
  }
  
  int main()
  {
    int a, b;
    cout << "Enter the Index no." << endl;
    cin >> a;
    cout << "Enter the value that u want to enter :" << endl;
    cin >> b;
  
    Insert(a, b);
  }

Code Explanation:

The program starts by defining a function called Insert. This function takes two arguments - index and val.

Inside the function, an integer array A is defined and initialized with some values {1, 2, 3, 4, 5}.

The length of the array A is calculated using the formula sizeof(A) / sizeof(A[0]). This is done to ensure that the loop that comes later does not go out of bounds.

The function checks if the index value passed by the user is within the bounds of the array A. If it is, then the program proceeds with the insertion of the new value.

A for loop is used to shift all the elements of the array after the given index position to the right by one position.

The new value passed by the user is then inserted at the index position using the statement A[index] = val.

The length of the array is then incremented by one.

Finally, the updated array A is printed to the console using another for loop.

I hope this explanation helps! Let me know if you have any further questions.

Inserting Elements into an Array

Data structure questions with story like explanation.

First, let's take a look at the program code: Java

C++ code:

Leave a comment