Question

I have two List’s that contain a object of Tag like List i need to find excluded and included to do an update operation how do find the difference in them both since they contain a Tag object. Can you use Contains function with a Tag object inside the list need some help.

Im using asp.net 2.0 so please if you can help me do it in that language please.

List<Tag> tag1 = new List<Tag>()  
tag1.Add(new Tag("Apples"));  
tag1.Add(new Tag("Oranges"));  
tag1.Add(new Tag("Pears"));  

List<Tag> tag2 = new List<Tag>()  
tag2.Add(new Tag("Apples"));  
tag2.Add(new Tag("Bananas"));  

txtExcluded.Text = list1;  
txtIncluded.Text = list2  

Answer 1

You could implement IEquatable<T>:

public class Tag : IEquatable<Tag>
{
    public Tag(string text)
    {
        Text = text;
    }
    public string Text { get; set; }

    public bool Equals(Tag other)
    {
        return other != null && string.Equals(Text, other.Text);
    }

    public override bool Equals(object obj)
    {
        return Equals(obj as Tag);
    }

    public override int GetHashCode()
    {
        return (Text ?? string.Empty).GetHashCode();
    }
}

Now the Contains method could work like this:

var list = new List<Tag>(new[]
{
    new Tag("Apples"),
    new Tag("Oranges"),
    new Tag("Pears"),
});

var tag = new Tag("Pears");
bool isContains = list.Contains(tag); // returns true