IEnumerable vs. List in LINQ: When Should I Use Each?

When the linq query uses IenuMerable and List

In .NET,

and

are the two basic data structures that indicate the object sequence. Both can be used together with the expression formula of Linq (Language Integration) to perform data conversion and aggregation, but they are different in terms of behavior and performance characteristics. IEnumerable List Entrectional behavior

is an interface that defines the behavior of the iterative element sequence. It provides the method, which returns an object of the interface. When you iterate the collection, the enumers traversed one element at one time.

In the code of code you provide, the type of IEnumerable variable is GetEnumerator(). When you debug and check it, you will notice members such as "Inner" and "OUTER". These members cannot be directly accessed in the IEnumerator instance. These members are part of the internal implementation of Linq and the underlying query pipeline. IEnumerable

"Inner" members usually include the intermediate result of the Linq expression before the application of any further conversion or screenter. It is particularly useful for complex debugging inquiries.

sel Performance precautions IEnumerable<animal> List<animal> In terms of performance,

usually provides better flexibility and optimization ability. The Linq expression is delayed, which means that they can only be executed when you enumerate the sequence. This allows the compiler and running query optimization and delayed evaluation in the background.

On the other hand, use the

method to convert to to force the query immediately and load all the results to the memory. If you need to access data multiple times, this may be more efficient because it eliminates duplicate expenses.

Generally speaking, when you only need to iterate the sequence and want to use a delay evaluation, it is recommended to use IEnumerable. If you need to access the data multiple times or you need to store it in the static data structure, it can be converted to

to improve performance.

.ToList() Specific examples IEnumerable List

The code you provides demonstrates how to use

to perform a more efficient database query. By maintaining the initial query (allSpotted ()) as IEnumerable, you can use List and

to screen it without performing the entire query multiple times.

However, if you need to enumerate the leopard and dumplings many times, it will be converted to a list to use more efficient. In this way, each set of database queries will be performed only once.

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