在使用linq查询的运算符中

Question

I have a list of items (InputList). Along with this I have a list of names (Names). Now I need only those items from InputList whose names are present in the Names list.

One solution is that I do a loop on Names list and check if it is present in InputList or not.

foreach (var name in names)
{
    var result = InputList.FirstOrDefault(i => i.Name == name);
    if (result != null)
        outputList.Add(result);
}

There is IN operator in SQL in which we provide list and query returns desired result. Can I achieve the same using Linq?

Answer 1

That you want is the following:

var result = inputList.Where(x=>Names.Contains(x.Name));

the above query selects all the elements of inputList, whose name is contained in the Names list.

The signature of Contains method is bool Contains(T item) , where T is the type of objects that are contained in your list. If the item you pass to this method is contained in your list returns true. Otherwise, it returns false.

For further documentation on the Contains method, please have a look here .