How to use IndexOf() method of List<object>

Question

All the examples I see of using the IndexOf() method in List are of basic string types. What I want to know is how to return the index of a list type that is an object, based on one of the object variables.

List<Employee> employeeList = new List<Employee>();
employeeList.Add(new Employee("First","Last",45.00));

I want to find the index where employeeList.LastName == "Something"

Answer 1

int index = employeeList.FindIndex(employee => employee.LastName.Equals(somename, StringComparison.Ordinal));

Edit: Without lambdas for C# 2.0 (the original doesn't use LINQ or any .NET 3+ features, just the lambda syntax in C# 3.0):

int index = employeeList.FindIndex(
    delegate(Employee employee)
    {
        return employee.LastName.Equals(somename, StringComparison.Ordinal);
    });

Answer 2

public int FindIndex(Predicate<T> match);

Using lambdas:

employeeList.FindIndex(r => r.LastName.Equals("Something"));

Note:

// Returns:
//     The zero-based index of the first occurrence of an element that matches the
//     conditions defined by match, if found; otherwise, –1.

EDIT: Beaten

Answer 3

you can do this through override Equals method

class Employee
    {
        string _name;
        string _last;
        double _val;
        public Employee(string name, string last, double  val)
        {
            _name = name;
            _last = last;
            _val = val;
        }
        public override bool Equals(object obj)
        {
            Employee e = obj as Employee;
            return e._name == _name;
        }
    }

Answer 4

Sorry, One more for good measure :)

int index = employees.FindIndex(delegate(Employee employee){return employee.LastName == "Something";});

Edit: - Full Example in .NET 2.0 Project.

class Program
{
    class Employee { public string LastName { get; set; } }
    static void Main(string[] args)
    {
        List<Employee> employeeList = new List<Employee>();
        employeeList.Add(new Employee(){LastName="Something"});
        employeeList.Add(new Employee(){LastName="Something Else"});
        int index = employeeList.FindIndex(delegate(Employee employee) { return employee.LastName.Equals("Something"); });
        Console.WriteLine("Index:{0}", index);
        Console.ReadKey();
    }
}