Question

After looking on MSDN, it’s still unclear to me how I should form a proper predicate to use the Find() method in List using a member variable of T (where T is a class)
For example:

public class Name
{
    public string FirstName;
    public string LastName;
    public String Address;
    public string Designation;
}

String[] input = new string[] { "VinishGeorge", "PonKumar", "MuthuKumar" };
//ConCatenation of FirstName and Lastname

List<Name> lstName = new List<Name>();

Name objName = new Name();
// Find the first of each Name whose FirstName and LastName will be equal to input(String array declard above).

for(int i =0;i<lstName.Count;i++)
{
    objName = lstName .Find(byComparison(x));
    Console.Writeline(objName .Address + objName.Designation);
}

What should my byComparison predicate look like?

Answer 1

It’s not clear why you’re looping and calling Find. Normally you’d call Find not in a loop – it will loop for you. Anonymous methods are your friends here though:

Name found = lstName.Find(delegate(Name name) {
                              return name.FirstName + name.LastName == x;
                          });

If you’re using C# 3 (even targeting .NET 2) you can use a lambda expression instead:

Name found = lstName.Find(name => name.FirstName + name.LastName == x);

EDIT: To find all names in input you can use:

List<Name> matches = lstName.FindAll(delegate(Name name) {
                               string combined = name.FirstName + name.LastName;
                               return input.Contains(combined);
                           });

Note that this won’t be terribly efficient as it will look through the whole of input for a match on every Name. However, the more efficient alternatives are more complicated – I think it’s important for you to understand how this code works to start with.