Remove from list items that have fields equal to some item fields

Question

Here is my code:

public class Person
{
    public int age;
    public int grade;
    public string name;
}

List<Person> _list = new List<Person>();
// .... add lots of items
var personToRemove = new Person {age = 99, grade = 7, };

How to write a command that removes from _list all persons what have the same age and grade values that personToRemove has.

Answer 1

You have to use .RemoveAll() with predicate to remove all persons with matching details in personToRemove person object.

So your query will be.

int totalRemoved = _list.RemoveAll(x => x.age == personToRemove.age && x.grade == personToRemove.grade);

Input:

_list.Add(new Person { age = 99, grade = 7 });
_list.Add(new Person { age = 87, grade = 7 });
_list.Add(new Person { age = 57, grade = 8 });

Output:

Edit:

You can also use traditional looping for elegant way to remove match person from list of persons.

for (int i = _list.Count - 1; i >= 0; i--)
{
    if (_list[i].age == personToRemove.age && _list[i].grade == personToRemove.grade)
    {
        _list.RemoveAt(i);
        break;
    }
}