Insertion Sort in C#


This article explains Insertion Sort in C#. Another simple sorting algorithm is the Insertion Sort. Basically, this algorithm works by first virtually dividing the list in two parts. While, the first part belongs to the sorted list, the other part is unsorted. Further, the agorithm picks an element from the unsorted part and inserts it in the correct place in the sorted part of the list.

An Example of Performing Sorting Using Insertion Sort

In order to demonstrate insertion sort, let us assume that we need to sort this list [9, 3, 2, 1, 5, 8]. Further, the sorted part contains only the first element. Whereas the unsorted part contains rest of the elements. So, the element in green color belongs to the sorted part of the list. While, those in red color belong to the unsorted part.

[9, 3, 2, 1, 5, 8]. At first, the algorithm compares element 3 with 9 and places it at first position and shift tle element 9. So the sorted list has two elements [3, 9].

[3, 9, 2, 1, 5, 8]. Further, it places the element 2 at its correct place.

[2, 3, 9, 1, 5, 8]. After that, it compares element 1 with each element in the sorted part and places the element 1 at first postion.

[1, 2, 3, 9, 5, 8]. Similarly, it takes 5 as the next element and compares it with 9. Again, it compares 5 with 3. Since, it is larger than 3, so it places 5 after 3.

[1, 2, 3, 5, 9, 8]. Likewise, the element 8 is placed before 9. Finally, the whole list is sorted.

[1, 2, 3, 5, 8, 9]

Implementation of Insertion Sort in C#

The following code shows Implementation of Insertion Sort in C#. Here, the variable i in the InsertionSort() function represents the unsorted part. While, j represents an element in the Sorted part.

using System;

namespace InsertionSort
    class Program
        static void Main(string[] args)
            int[] myarray = { 4, 1, 9, -13, 90, 56, 81, 34, -2, -15, 60, 88 };
            Console.WriteLine("Array before sorting...");
            foreach (int x in myarray)
                Console.Write(x + "  ");
            Console.WriteLine("\nArray after sorting...");
            foreach (int x in myarray)
                Console.Write(x + "  ");
    class Sort
        public static void InsertionSort(int[] a1)
            int j, x;
            for(int i=1;i<a1.Length;i++)
                x = a1[i];
                j = i - 1;
                while((j>=0) && (a1[j]>x))
                    a1[j + 1] = a1[j];
                a1[j + 1] = x;


Sorting an Array using Insertion Sort in C#
Sorting an Array using Insertion Sort in C#

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