how to compare two arrays of objects

Question

i have an object called Person. It has properties First, Last, Age, etc . . .

I have two arrays of Person objects.

I want to have some function to take two arrays

Person[] firstlist =  . .
Person[] secondList =  . .

and have it spit out two new arrays

Person[] peopleinFirstListandNotSecond
Person[] peopleinSecondListandNotFirst

Since these are not string arrays, i would want to do a compare on first and last name and age to determine if its the same person

Answer 1

Here is a linq function (IEnumerable<T>.Except(...)) that will do what you need.

http://msdn.microsoft.com/en-us/library/bb336390.aspx

Answer 2

Implement IComparable (see SO: IComparable and Equals) and then loop through each list, building the required two output lists.

Answer 3

You could write a comparer (implement the IEqualityComparer interface) then use it with the Except extension method, as other posters have noted.

Or, you could just do the comparison within the lambda eg

var peopleinFirstListAndNotSecond =     
    firstList.
    Where( p => 
            !secondList.Any( s => 
                s.Age == p.Age && 
                s.FirstName == p.FirstName && 
                s.SecondName == p.SecondName
         ) 
    );