Searching if value exists in a list of objects using Linq

Question

Say I have a class Customer which has a property FirstName  Then I have a List lt Customer gt    Can LINQ be used to find if the list has a customer with Firstname    John  in a single statement   how

User · Accepted Answer

LINQ defines an extension method that is perfect for solving this exact problem:

using System.Linq;
...
    bool has = list.Any(cus => cus.FirstName == "John");

make sure you reference System.Core.dll, that's where LINQ lives.

User · Answer

The technique i used before discovering  Any     var hasJohn    from customer in list       where customer FirstName     John        select customer  FirstOrDefault      null

User · Answer

Another possibility  if  list Count customer   gt  customer Firstname     John    gt  0       bla

User · Answer

Using Linq you have many possibilities  here one without using lambdas     assuming list is a List lt Customer gt  or something queryable    var hasJohn    from customer in list          where customer FirstName     John           select customer  Any

User · Answer

zvolkov s answer is the perfect one to find out if there is such a customer  If you need to use the customer afterwards  you can do   Customer customer   list FirstOrDefault cus   gt  cus FirstName     John    if  customer    null           Use customer     I know this isn t what you were asking  but I thought I d pre-empt a follow-on question     Of course  this only finds the first such customer    to find all of them  just use a normal where clause

User · Answer

List lt Customer gt  list        Customer john   list SingleOrDefault customer   gt  customer Firstname     John      john will be null if no customer exists with a first name of  John

User · Answer

customerList Any x  gt x Firstname     John

User · Answer

One option for the follow on question  how to find a customer who might have any number of first names    List lt string gt  names   new List lt string gt    John    Max    Pete     bool has   customers Any cus   gt  names Contains cus FirstName      or to retrieve the customer from csv of similar list     string input    John Max Pete   List lt string gt  names   input Split      ToList    customer   customers FirstOrDefault cus   gt  names Contains cus FirstName

User · Answer

Try this  I hope it helps you    if  lstCustumers Any cus   gt  cus Firstname     John              TODO CODE

[c#] Searching if value exists in a list of objects using Linq

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