C#/.NET interview Question – Can you explain why Array is faster than Arraylist?

C#/.NET interview Question – Can you explain why Array
is faster than Arraylist?

Answer: Let’s demonstrate an example to prove that how arrays are faster than
arraylist for that go to visual studio and create a simple window
application with a button and two labels like below diagram.111Below is the code snippet.

using System.Collections;// import this namespace to access arraylist.
using System.Diagnostics;// import this namespace to access Stopwatch.
namespace ArrayandArrayList
{
    public partial class Form1 : Form
    {
        int[] Array = new int[1000]; // here array is declared.
        ArrayList objArraylist = new ArrayList();// here array list is declared.
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Stopwatch objWatch = new Stopwatch();
            Stopwatch objWatch1 = new Stopwatch();
            objWatch.Start();
            for(int i=0;i<1000;i++)
            {
                Array[i] = DateTime.Now.Second;
            }
            foreach (int i in Array)
            {

            }
            objWatch.Stop();
            label1.Text = objWatch.ElapsedTicks.ToString();
            objWatch1.Start();
            for (int i = 0; i < 1000; i++)
            {
                objArraylist.Add(DateTime.Now.Second.ToString());
            }
            foreach (object i in objArraylist)
            {
            }
            objWatch1.Stop();
            label2.Text = objWatch1.ElapsedTicks.ToString();
        }
    }
}

In the above code, I have used Stopwatch to record the time taken by the
array and arraylist to performance actions.

The Output look like below diagram.

qwqwqw.png

Conclusion: -As in ArrayList lots of Boxing and UnBoxing are done
therefore its performance is slower than Array because in Array there is no
type casting.

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Regards,

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About c# and .NET Interview questions

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