Coding

In .NET What is the difference between Where and Select?

flam79

The Where and Select are two methods provided by LINQ (Language Integrated Query) in .NET to manipulate collections. They each serve a different purpose:

  1. Where: This method is used to filter a collection. It returns a new collection that includes only the elements of the original collection that satisfy a given condition. You pass in a predicate function, and Where applies this function to each item in the collection. If the function returns true for an item, that item is included in the new collection.

    Example:
    var evenNumbers = list.Where(x => x % 2 == 0); This would give you a new collection with only the even numbers from the original list.

  2. Select: This method is used for projections. It transforms each element of a collection into a new form. You pass in a transformation function, and Select applies this function to each item in the collection to produce a new item for the new collection.

    Example:
    var squares = list.Select(x => x * x);

    This would give you a new collection where each number is the square of the corresponding number in the original list.

The key difference is that Where is for filtering and Select is for transforming. You can also chain these methods together to perform more complex operations. For example:

var evenSquares = list.Where(x => x % 2 == 0).Select(x => x * x);

This would give you a new collection containing the squares of the even numbers in the original list.