This post is quick intro for beginners. I’ll introduce you to 2 Linq methods Select and Where. We use those functions to manipulate data set.
All 2 can be applied to all types implementing IEnumerable interface. It means that you can apply them to data retrieved from database (
IQueryable), list (
IEnumerable), arrays (which also implements
IEnumerable) and others.
It’s important to know that each one of those functions return new IEnumerable. Even if we execute these methods on array (e.g.
int) it returns enumerable (e.g.
IEnumerable<int>). Note that it works a bit different for
IQueryable and database operations. Since this is an introductory level post I’ll show you how to use them using array based examples.
With Select we can map/project data to new form. It means that we can use it make something with every element.
We use Where when we want to filter data. So it checks every element and returns only elements which matches critera.
Chaining Select and Where
Since both of these functions return IEnumerable we can chain them. Take a look at this example: