select object which matches with my condition using linq

Question

I have list of type Person which has 3 properties Id, Name, Age

var per1 = new Person((1, "John", 33);
var per2 = new Person((2, "Anna", 23);

var persons = new List<Person>();
persons.Add(per1);
persons.Add(per2);

using linq I want to select person which age matched with my input, for example 33.

I know how to use any but I dont know how to select object which matches with my condition.

Answer 1

You can use Enumerable.Where and it will return all the matching elements collection.

var res = persons.Where(c=>c.AttributeName == 23);

If you want to ensure you have only match you can use single.

var res = persons.Single(c=>c.AttributeName == 23);

Single Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence.

Answer 2

For one match:

var match = persons.Single(p => your condition);

For many matches, use persons.Where(condition). There are also many variants of picking just one person, such as FirstOrDefault, First, Last, LastOrDefault, and SingleOrDefault. Each has slightly different semantics depending on what exactly you want.