Hi, in this video, we're going to think about the var data type and how to instantiate and declare anonymous objects. We're using some ready-written code in this particular demo.

In fact, we're building on the previous program, but before we actually go back to the underlying code of that program, there's a couple of lines here that I've added that introduce the concept of anonymous types.

You'll notice here that I'm creating a new object using the new operator, but I've not specified a class name as I did in previous examples. And that makes this anonymous type. I can specify on the fly properties I want this object to have, and I can set those properties to these specific values.

But over on the left-hand side, what do I define this thing as? I can't define it as an integer, I can't define it as a string because it's more than that. So, the only thing I, I can use is an operator or, or a data type known as var.

You'll notice that when I hover the mouse over the field name, IntelliSense tells me that I've got an anonymous type, it uses a little notation quote lowercase A, and it tells me what the properties of that anonymous type are.

That means that on the next line of code I can refer to this newly created variable and refer to its properties, and I can print them out to the console.

So, if I set a break point here, I can launch the application and get myself down to that break point, and we can see those details being printed out.

And down the foot of here, that's that line of code, it's printed out the details, 99 Rover Canis, which is the details of that anonymous object type. Next thing I'm going to do is embed that concept into a LINQ query.

So, I've got a simple LINQ query here from pet in pets select new, but again, no mention of a class name, so I'm creating an instance of an object with these various properties, the properties are coming from the values associated with the pet objects in the pets collection, and in fact, what this thing is returning is not a single object, but a collection of anonymous objects, and they're all of the same type, but they're all-, there, there's no type name for them.

So, again, I have no option but to call them-, define them as vars. It tells me that this thing hasn't been created as yet, and so I can look at the next line of code and see that we're going to for-each around that collection, we're going to refer to each object in turn as pt, and we can then home in and pull on-, and pull in on those properties, ID, Name, pet Type and Breed, even though they're not associated with any class that's been pre-defined.

Carrying on with the code and running to that breakpoint, we see that it does just print out details of those anonymous objects, ID, Name, Type, and Breed.

So, in this video, we've seen how to create and define anonymous types. We don't have any pre-defined class names for them, which means the only way that we can refer to them by way of a data type is by using the var keyword.

Practical example of anonymous (var) classes and objects

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