Find a KeyValuePair inside a List

Question

Suppose I have

 List<KeyValuePair<int, string>> d

I know the string but I want to find its integer. How do I find the keyvaluepair inside this List?

Answer 1

You'd write this:

var result = d.Where(kvp => kvp.Value == "something");

result would contain all the KeyValuePairs with a value of "something"

Answer 2

You could use LINQ Single or SingleOrDefault if the item is unique:

KeyValuePair<int, string> v = d.SingleOrDefault(x => x.Value == "mystring");
int key = v.Key;

If the item is not unique, then you could use LINQ Where:

var v = d.Where(x => x.Value == "mystring"); //the results would be IEnumerable

And if the item is not unique, but you want to get the first one among the non-unique items, use First or FirstOrDefault

var v = d.FirstOrDefault(x => x.Value == "mystring");
int key = v.Key;