Check value in list

Question

I have a general list of values. I want to check if an identifier exists in this general list.

What is the easiest way to do this?

Example

List<someCustomObject> mylist = GetCustomObjectList(); int idToCheckFor = 12; 

I want to see if 12 exists in any of the user objects in the list by checking each someCustomObject.Id = idToCheckFor

If a match is found, I’m good to go, and my method will return bool true. I'm just trying to find out if there is an easy way, rather than iterating over each item in the list to see if idToCheckFor == someCustomObject.id and setting the variable to true if a match is found. I am sure there will be a better way to do this.

Answer 1

If you are using .NET 3.5, it is easy to use LINQ for objects:

 return myList.Any(o => o.ID == idToCheckFor); 

In addition, the loop is truly your only option.

Answer 2

 Boolean b = myList.Find(obj => obj.id == 12) != null; 

Answer 3

LINQ makes life easier

 mylist.Where(x => x.id == idToCheckFor).Any() 

thanks

Answer 4

I think you are using the wrong data structure for this. What you need:

 Dictionary<int, someCustomObject> myDictionary = GetCustomObjectDictionary(); 

Now you can easily check if an identifier exists with fantastic performance.

 return myDictionary.ContainsKey(idToCheckFor); 

Answer 5

  bool found = mylist.Any(p => p.Id == idToCheckFor); 

Answer 6

 bool bExists = myList.Any(x=>x.id == idToCheckFor); 

Answer 7

 if(mylist.Any(Item => Item.Id == idToCheckFor)) { do(); } 

Answer 8

return myList.Exists (item => item.Id == idToCheckFor);

For linq resources you can check 101 linq sample

Answer 9

Use LINQ to Objects. Something like the following:

 var result = from l in mylist where l.id = 12 select l; return result != null;