Question

I searched all over the internet to find an answer for this. I am looping through two lists (list1 and list2) with nested for loops and removing duplicate records in first list based on three criteria. If all records in these two lists match each other, I get an out of bounds error. I assume it happens when I remove all the items from the first list, and when it finally reduces to 0, and does not have any records to loop through, but putting an if statement to check the count of the first list (if inbox_emails_filtered_contacts.Count > 0) does not help either. Please let me know if any of you can tell me why this errors out.

Outlook Add-in in C#.net

for (int i = 0; i < list1.Count; i++)
{
    for (int j = 0; j < list2.Count; j++)
    {
        if (list1.Count > 0)
        {
            if ((list1[i].username == registered_user)
                && (list1[i].from_email.ToLower() == list2[j].from_email.ToLower())
                && (list1[i].email_subject == list2[j].email_subject)
                && (list1[i].email_timestamp.ToLongDateString() == list2[j].email_timestamp.ToLongDateString()))
            {
                //Remove the duplicate email from inbox_emails_filtered_contacts
                list1.RemoveAt(i);
            }
        }
    }
}

Answer 1

here is an implementation of an Email class

class Email:IComparable<Email>
{
    private static int _Id;

    public Email()
    {
        Id = _Id++;
    }

    public int Id { get; private set; }
    public string UserName { get; set; }
    public string Body { get; set; }
    public string Subject { get; set; }
    public DateTime TimeStamp { get; set; }

    public override int GetHashCode()
    {
        return UserName.GetHashCode() ^ Body.GetHashCode() ^ Subject.GetHashCode();
    }

    public int CompareTo(Email other)
    {
        return GetHashCode().CompareTo(other.GetHashCode());
    }

    public override string ToString()
    {
        return String.Format("ID:{0} - {1}", Id, Subject);
    }

    public override bool Equals(object obj)
    {
        if (obj is Email)
            return CompareTo(obj as Email) == 0;
        return false;
    }

}

and 2 ways of getting the diff.

        var list1 = new List<Email>();
        var ran = new Random();
        for (int i = 0; i < 50; i++)
        {
            list1.Add(new Email() { Body = "Body " + i, Subject = "Subject " + i, UserName = "username " + i, TimeStamp = DateTime.UtcNow.AddMinutes(ran.Next(-360, 60)) });
        }
        var list2 =  new List<Email>();

        for (int i = 0; i < 50; i++)
        {
            if (i % 2 == 0)
                list2.Add(new Email() { Body = "Body " + i, Subject = "Subject Modifed" + i, UserName = "username " + i, TimeStamp = DateTime.UtcNow.AddMinutes(ran.Next(-360, 60)) });
            else 
                list2.Add(new Email() { Body = "Body " + i, Subject = "Subject " + i, UserName = "username " + i, TimeStamp = DateTime.UtcNow.AddMinutes(ran.Next(-360, 60)) });

        }


        foreach (var item in list2.Intersect<Email>(list1))
        {
            Console.WriteLine(item);
        }

        foreach (var item in list1)
        {
            for (int i = 0; i < list2.Count; i++)
            {

                if (list2[i].Equals(item))
                {
                    Console.WriteLine(item);
                    list2.RemoveAt(i);
                    break;
                }
            }
        }

        Console.WriteLine(list2.Count);