从C＃4.0中的元组列表中查找和删除元组

Question

I have created a list of tuples:

static List<Tuple<string, string>> Alt;

The user adds to this list:

Alt.Add(new Tuple<string, string>(tbAlt.Text, ""));

What is the best way to find a Tuple based on the first string (ie the tbAlt.Text ) and either delete it or modify the second string?

I am new to using Tuples and lists :)

Many thanks for any help!

Answer 1

Your list of tuples looks much like dictionary. Consider using it instead - Dictionary<string,string> . It already has methods for retreiving value by key, deleting it, etc

If there could be multiple values for the same key, you can use Lookup class.

Answer 2

It appears the first string must be unique or you would not find a (singular)

Why are you using List<Tuple<string, string>> ?

Why not Dictionary<string,string> ?

Dictionary<TKey, TValue>.ContainsKey is very very fast.

Dictionary.ContainsKey

Answer 3

You could use List<T>.FindIndex to find the matching index, then replace as needed.

int index = Alt.FindIndex(t => t.Item1 == tbAlt.Text);

if (index != -1)
{
   // Modify
   Alt[index] = Tuple.Create(tbAlt.Text, "NewText");

   // Remove:
   Alt.RemoveAt(index);
}

Answer 4

Find tuple based on value of first string ( Item1 ):

var t = Alt.FirstOrDefault(i => i.Item1 == "SomeString");
if(t != null)
{
    // delete
    Alt.Remove(t);
}

From comments:

You can't modify value of second item ( Item2 ), because tuples are immutable, so you 'll have to remove it and add it again.

Answer 5

If you are sure the list contain your item :

Alt.Remove(Alt.First(i => i.Item1 == tbAlt.Text));

However, in order to modify a Tuple, you must create a new one.

if (Alt.Any(i => i.Item1 == tbAlt.Text))
{
    Alt.Remove(Alt.First(i => i.Item1 == tbAlt.Text));
    Alt.Add(new Tuple<string, string>(tbAlt.Text, "Something New"));
}