What Is Insertion Sort in C Data Structure?


Scott Campbell

What Is Insertion Sort in C Data Structure?

When it comes to sorting algorithms, insertion sort is a simple yet efficient method. It is especially useful for small data sets or partially sorted data. In this article, we will explore the concept of insertion sort and how it works in the context of C data structures.

The Basics of Insertion Sort

Insertion sort follows the analogy of sorting a deck of playing cards. Just like we would arrange a deck by picking one card at a time and placing it at its correct position, insertion sort works by dividing the array into two parts: the sorted subarray and the unsorted subarray.

To perform an insertion sort, you start with the second element in the array and compare it with each element in its left until you find its correct position. This process is repeated for all elements in the array until the entire list is sorted.

An Example Implementation

To illustrate how insertion sort works, let’s consider an example implementation in C:

#include <stdio.h>

void insertionSort(int arr[], int n) {
   int i, key, j;
   for (i = 1; i < n; i++) {
       key = arr[i];
       j = i - 1;

       while (j >= 0 && arr[j] > key) {
           arr[j + 1] = arr[j];
           j = j - 1;
       arr[j + 1] = key;

int main() {
   int arr[] = {12, 11, 13, 5, 6};
   int n = sizeof(arr)/sizeof(arr[0]);

   insertionSort(arr, n);

   printf("Sorted array: \n");
   for (int i = 0; i < n; i++)
       printf("%d ", arr[i]);
   return 0;

In this implementation, we define a function called insertionSort that takes an array and its size as parameters. The function iterates through the array, starting from the second element (index 1), and compares it with each preceding element to find its correct position.

The sorted subarray is expanded incrementally, with each iteration placing the current element at its appropriate place. Finally, the sorted array is printed using the printf function.

Advantages and Disadvantages of Insertion Sort

Insertion sort has several advantages:

  • Simplicity: Insertion sort is relatively easy to understand and implement.
  • Efficiency for Small Data Sets: It performs well for small data sets or partially sorted data.

However, insertion sort also has some disadvantages:

  • Inefficiency for Large Data Sets: Compared to more advanced sorting algorithms like merge sort or quicksort, insertion sort becomes less efficient when dealing with large data sets due to its time complexity of O(n^2).
  • Lack of Adaptability: Insertion sort does not adapt well to changes in input order. Even a small change in the input may require a significant number of shifts to be made.

In Conclusion

In summary, insertion sort is a simple yet effective algorithm for sorting data in C. It works by gradually expanding a sorted subarray and placing each new element at its correct position. While insertion sort may not be the most efficient choice for large data sets, it shines when dealing with small data sets or partially sorted data.

Remember to consider the advantages and disadvantages of insertion sort when choosing a sorting algorithm for your specific use case. Happy coding!

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