[c#] What is the difference between for and foreach?

I prefer the FOR loop in terms of performance. FOREACH is a little slow when you go with more number of items.

If you perform more business logic with the instance then FOREACH performs faster.

Demonstration: I created a list of 10000000 instances and looping with FOR and FOREACH.

Time took to loop:

• FOREACH -> 53.852ms
• FOR -> 28.9232ms

Below is the sample code.

class Program
{

    static void Main(string[] args)
    {
        List<TestClass> lst = new List<TestClass>();
        for (int i = 1; i <= 10000000; i++)
        {
            TestClass obj = new TestClass() {
                ID = i,
                Name = "Name" + i.ToString()
            };
            lst.Add(obj);
        }

        DateTime start = DateTime.Now;
        foreach (var obj in lst)
        {
            //obj.ID = obj.ID + 1;
            //obj.Name = obj.Name + "1";
        }
        DateTime end = DateTime.Now;
        var first = end.Subtract(start).TotalMilliseconds;

        start = DateTime.Now;
        for (int j = 0; j<lst.Count;j++)
        {
            //lst[j].ID = lst[j].ID + 1;
            //lst[j].Name = lst[j].Name + "1";
        }
        end = DateTime.Now;
        var second = end.Subtract(start).TotalMilliseconds;
    }
}

public class TestClass
{
    public long ID { get; set; }
    public string Name { get; set; }
}

If I uncomment the code inside the loop: Then, time took to loop:

• FOREACH -> 2564.1405ms
• FOR -> 2753.0017ms

Conclusion
If you do more business logic with the instance, then FOREACH is recommended. If you are not doing much logic with the instance, then FOR is recommended.