I don't know which control caused the event.
sender is the control that causes the event. It's a rule of windows forms - the event handler shall be an invokable member with a first argument that is the control that raised the event
I am saying "Getting the index of the media player in the media players array is pointless because the only thing you can do with it on the media players array is get the media player again, but you already know the media player"
You must be planning on doing something else with the index, not related to the media players array. Perhaps, for example, you're then planning to use it to index the picture boxes array, because you tie media players and pictureboxes together for some purpose and have made the design decision that media player X is associated with picture box X (I.e. it is not a coincidence that you have 16 of each)
What we are saying is there are better, cleaner, easier ways to tie things together than "this media player at index 4 and that picturebox at index 4, serve a related purpose"
At its most simplistic, for example, a windows control has a Tag property that can store anything. The fourth media player's Tag can reference the fourth picturebox so you could say:
var mp = sender as MediaPlayer;
var pb = mp.Tag as PictureBox;
You set the Tag when you're loading the controls; the moment when you know both controls, probably some loop in the constructor of the form that makes a new MP, makes a new PB, adds them to the controls collection, binds their events etc.. that's the moment you do
myNewMp.Tag = myNewPicturebox to form the association, so you can later retrieve them
Rather than
var x = 0;
while(!object.ReferenceEquals(sender, mediaplayers[x])) x++);
var pb = pictureboxes[x];
var mp = sender as MediaPlayer;
It'll work, but it's not very clean. If there are 7 different things you want to track in relation to a media player, instead of having 7 arrays of different types, make a class with 7 properties and store an instance of it in the Tag. This is how we work in C#. If we want to store information about people we don't do it like this:
var names = new string[10];
var ages = new int[10];
var birthdays = new DateTime[10];
//John, 23, born 2000
names[0] = "John";
ages[0] = 23;
birthdays[0] = new(2000,1,1);
We do this:
class Person{ //keep related info together
public string Name{get;set;}
public int Age{get;set;}
public DateTime{get;set;}
}
...
var people = new Person[10];
people[0] = new(){ Name = "John", Age = "23", Birthday = new(2000,1,1) };
(Yes and then we would make Age a readonly property that calculates the years from the birthday.. it's an example)
