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C#/.NET interview Question - Who perform faster?Array or Arraylist

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.

Below 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()

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

label1.Text = objWatch.ElapsedTicks.ToString();
for (int i = 0; i < 1000; i++)
foreach (object i in objArraylist)
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.

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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Shivprasad koirala Koirala
I am a Microsoft MVP for ASP/ASP.NET and currently a CEO of a small E-learning company in India. We are very much active in making training videos , writing books and corporate trainings. Do visit my site for .NET, C# , design pattern , WCF , Silverlight , LINQ , ASP.NET , ADO.NET , Sharepoint , UML , SQL Server training and Interview questions and answers
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