Count() a specfic attribute within a list c#

Question

if (gardenvlist.Count() == getava.Count())
{

}
else if(oceanvlist.Count() == getava.Count())
{

}
else if (cityvlist.Count() == getava.Count())
{

}

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Answer 1

If I understand your question correctly, you can pass in a lambda expression to Count() to selectively count items based on properties then compare that to whatever you'd like. Something like this:

if (gardenvlist.Count()== getava.Count(x => x.Name == "GardenName"))

Note you will need to add the following using statement: using System.Linq

Answer 2

Use the overload which takes a predicate. Here is the signature:

public static int Count<TSource>(this IEnumerable<TSource> source, 
    Func<TSource, bool> predicate);

Imaging you have this:

public class Room
{
    public string Name { get; set; }
}

Then you put them into a list:

var rooms = new List<Room>()
{
    new Room { Name = "Living" },
    new Room { Name = "Kitchen" }
};

You want to know how many rooms have the name "Living":

int count = rooms.Count(x => x.Name == "Living");

Answer 3

There is another overload of Count() that takes a lambda expression as a parameter where you can filter elements to count from the source collection.

Say you have a list of strings like this:

var list = new List<string>() {
   "a",
   "b",
   "c",
   "aa",
   "bbb"
};

Then you can use it like this:

var countSingles = list.Count(str => str.Length == 1);

This will count the elements of the list with length 1, so here it would return 3.