# C++ Insertion Sort

Here is Code for Insertion Sort in C++

• not the fastest sorting algorithm

Time Complexity is O(n^2), we can see the nested for loop!

``````#include <iostream>
using std::cout; using std::endl;

// Well the sorting algorith time complexity is O(n^2)
// We can see the nested for loop

void insertionSort(int arr[], int size)   // or int *array
{
// Size is the size (length) of the size array
int key, j;

for (int i = 1; i < size; i++ )
{
// i starts on 2nd index

key = arr[i];
// Key is the value we will compare to the left value

j = i - 1; // Value to Compare key with

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

}

void PrintArray(int arr[], int n)
{
for (int i = 0; i < n; i++)
{
cout << arr[i] << " ";
}
cout << endl;
}

int main()
{
int arr[] = { 12, 11, 13, 5, 6, 1, 9,0};
int n = sizeof(arr) / sizeof(arr[0]);

PrintArray(arr, n);
cout << "After insertion \n";
insertionSort(arr, n);
PrintArray(arr, n);

}
``````

Updated: