FAQ: What are enumerables in c#?

In C#, an Enumerable is an object like an array, list, or any other sort of collection that implements the IEnumerable interface. Enumerables standardize looping over collections, and enables the use of LINQ query syntax, as well as other useful extension methods like List.

What is enumerable and IEnumerable in C#?

IEnumerable is an interface. It is part of system. … This is the method the foreach loop uses loop through a collection and returns an IEnumerator Interface.An Enumerable class is part of Linq library and is a bunch of extension methods written for the IEnumerable interface.

What is IEnumerator in C# with example?

IEnumerable interface has a method called GetEnumerator() which returns an object implemented IEnumerator. Let’s do an example: PowersOfTwo class implements IEnumerable so any instance of this class can be accessed as a collection. Current returns the same element until MoveNext is called.

What is enumerable projects?

Projects each element of a sequence into a new form. Projects each element of a sequence to an IEnumerable&lt,T&gt,, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein.

What is IEnumerable and IQueryable in C#?

Querying data from a database, IEnumerable execute a select query on the server side, load data in-memory on a client-side and then filter data. Querying data from a database, IQueryable execute the select query on the server side with all filters. IEnumerable Extension methods take functional objects.

What is enumerable?

IEnumerable is an interface defining a single method GetEnumerator() that returns an IEnumerator interface. It is the base interface for all non-generic collections that can be enumerated. This works for read-only access to a collection that implements that IEnumerable can be used with a foreach statement.

What are collections in C#?

Collection classes are specialized classes for data storage and retrieval. These classes provide support for stacks, queues, lists, and hash tables. … These classes create collections of objects of the Object class, which is the base class for all data types in C#.

What is the difference between IEnumerable and IEnumerator in C#?

The main difference between IEnumerable and IEnumerator is IEnumerable works for the generic interface, and IEnumerator works for all non-generic interfaces. IEnumerable points to an object which can be enumerated, but IEnumerator is implemented using each statement for iteration. … It acts as an object.

What is IEnumerator function in C#?

IEnumerator is the base interface for all non-generic enumerators. Its generic equivalent is the System. Collections. … You must call the MoveNext method to advance the enumerator to the first element of the collection before reading the value of Current, otherwise, Current is undefined.

What is coroutine in C#?

A coroutine is a function that can suspend its execution (yield) until the given YieldInstruction finishes.

What is enumerable repeat in C#?

Enumerable. Repeat method is part of System. Linq namespace. It returns a collection with repeated elements in C#. Firstly, set which element you want to repeat and how many times.

What does enumerable mean in coding?

An enumerable property is one that can be included in and visited during for..in loops (or a similar iteration of properties, like Object. … If a property isn’t identified as enumerable, the loop will ignore that it’s within the object.

What is LINQ enumerable?

IEnumerable Type with LINQ

IEnumerable is a forward only collection and is useful when we already know the type of query result. In the below query, the result will be a list of employee that can be mapped (type cast) to the employee table.

When should I use IQueryable?

IQueryable uses Expression objects that result in the query being executed only when the application requests an enumeration. Use IQueryable when you have to run ad-hoc queries against data source like LinQ to SQL Server,Entity framework and other sources which implement IQueryable.

What is difference between IQueryable and list in C#?

List&lt,T&gt, is just an output format, and while it implements IEnumerable&lt,T&gt, , is not directly related to querying. In other words, when you’re using IQueryable&lt,T&gt, , you’re defining an expression that gets translated into something else.

Is IQueryable faster than IEnumerable?

IQueryable is faster than IEnumerable. In addition to Munesh Sharma’s answer:IEnumerable loads data in-memory and then apply filters to it one by one but IQueryable apply filters all at once and return the result.

What are enumerable properties?

Enumerable properties are those properties whose internal enumerable flag is set to true, which is the default for properties created via simple assignment or via a property initializer. Properties defined via Object. … Properties of an object can also be retrieved in total.

Is IEnumerable immutable?

If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 10 years ago. Just realized IEnumerable is immutable, what are other commonly used immutable generic interfaces?

What is IEnumerable in ASP NET MVC?

IEnumerable interface is used when we want to iterate among our classes using a foreach loop. The IEnumerable interface has one method, GetEnumerator, that returns an IEnumerator interface that helps us to iterate among the class using the foreach loop.

What is threading in C#?

Threading. Thread class is used for working with threads. It allows creating and accessing individual threads in a multithreaded application. The first thread to be executed in a process is called the main thread. When a C# program starts execution, the main thread is automatically created.

What is sealed class in C#?

A sealed class, in C#, is a class that cannot be inherited by any class but can be instantiated. The design intent of a sealed class is to indicate that the class is specialized and there is no need to extend it to provide any additional functionality through inheritance to override its behavior.

What is ref and out in C#?

ref is used to state that the parameter passed may be modified by the method. in is used to state that the parameter passed cannot be modified by the method. out is used to state that the parameter passed must be modified by the method.

What is difference between IList and list in C#?

The main difference between List and IList in C# is that List is a class that represents a list of objects which can be accessed by index while IList is an interface that represents a collection of objects which can be accessed by index. … Overall, List is a concrete type that implements the IList interface.

What is difference between list and IEnumerable?

One important difference between IEnumerable and List (besides one being an interface and the other being a concrete class) is that IEnumerable is read-only and List is not. So if you need the ability to make permanent changes of any kind to your collection (add &amp, remove), you’ll need List.

What is yield in C#?

The C# yield keyword, to put it simply, allows many calls to a body of code, referred to as an iterator, that knows how to return before it’s done and, when called again, continues where it left off – i.e. it helps an iterator become transparently stateful per each item in a sequence that the iterator returns in …

How does an IEnumerator work?

IEnumerator and IEnumerable are interfaces that all collections in C# implement and provide a way of iterating through all the values in a collection without needing to know how the collection stores these values. IEnumerable has a method called GetEnumerator that returns a class that implements IEnumerator.

Does list implement IEnumerable?

List implements IEnumerable, but represents the entire collection in memory. LINQ expressions return an enumeration, and by default the expression executes when you iterate through it using a foreach, but you can force it to iterate sooner using .

Is coroutine C# or Unity?

The C# compiler auto generates an instance of a class that backs coroutines. Unity then uses this object to track the state of the coroutine across multiple invocations of a single method.

Is coroutine a thread?

Threads. Coroutines are very similar to threads. However, coroutines are cooperatively multitasked, whereas threads are typically preemptively multitasked.

What does yield do in a coroutine?

The first thing to know about the yield() function is that it is a suspend function that is used in the context of Kotlin Coroutines. When yield() is invoked, it yields the thread (or thread pool) of the current coroutine dispatcher to other coroutines to run if possible.

What is enumerable range?

Range overview. It takes two arguments. First argument is the first number in sequence (e.g. 10, means that the first number in sequence is 10). It returns IEnumerable&lt,int&gt, which contains generated sequence. …

Does C Sharp do until?

The do-while loop starts with the do keyword followed by a code block and a boolean expression with the while keyword. The do while loop stops execution exits when a boolean condition evaluates to false. Because the while(condition) specified at the end of the block, it certainly executes the code block at least once.

How do I print a string multiple times in C#?

Repeat String X Times With the LINQ Method in C

We can use the Enumerable. Repeat() function of LINQ to repeat a string x number of times in C#. The Enumerable. Repeat(s, x) function takes two parameters, the string variable s and the integer variable x , the number of times that string variable must be repeated.

What is enumerable and non-enumerable?

Objects can have properties that don’t show up when iterated through the particular object using Object. keys() or for…in loop. Those type of properties are called as non-enumerable properties.

Are functions enumerable?

one of the basic concepts of the theory of algorithms. Function f is called enumerable if there exists an algorithm that transforms any object x, for which there exists a function f, into the object f(x) and that is not applicable to any other x for which f is not defined.

What is an enumerable in Ruby?

Enumeration refers to traversing over objects. In Ruby, we call an object enumerable when it describes a set of items and a method to loop over each of them.

What is FirstOrDefault C#?


Returns first element of a sequence, or a default value if no element is found. It throws an error Only if the source is null. you should use it, If more than one element is expected and you want only first element.

What is AsQueryable C#?


Converts an IEnumerable to an IQueryable.

Which is better IQueryable or IEnumerable?

So if you working with only in-memory data collection IEnumerable is a good choice but if you want to query data collection which is connected with database `IQueryable is a better choice as it reduces network traffic and uses the power of SQL language.

Should you return IQueryable or IEnumerable?

Returning IQueryable will definitely afford more flexibility to the consumers of the repository. It puts the responsibility of narrowing results off to the client, which naturally can both be a benefit and a crutch.

What is return type of IQueryable?

Linq. IQueryable is executed. // the expression tree associated with this object is executed.


Feature IEnumerable IQueryable
Custom Query No Support Supported

Is IQueryable faster than list?

GetList(context) might return an object backed by a custom LINQ provider (like an Entity Framework collection), then you probably want to leave the data cast as an IQueryable: even though your benchmark shows it being 20 times faster to use a list, that difference is so small that no user is ever going to be able to …

Which is better IEnumerable or list?

In terms of performance, the answer is it depends. If you need the results to be evaluated at once (say, you’re mutating the structures you’re querying later on, or if you don’t want the iteration over the IEnumerable&lt,T&gt, to take a long time) use a list.

What is difference between IEnumerable and IQueryable and list in C#?

IEnumerable is useful when we want to iterate the collection of objects which deals with in-process memory. IQueryable is useful when we want to iterate a collection of objects which deals with ad-hoc queries against the data source or remote database, like SQL Server.

What is deferred execution?

Deferred execution means that the evaluation of an expression is delayed until its realized value is actually required. It greatly improves performance by avoiding unnecessary execution. … This is called deferred execution.

How do you use AsEnumerable?

AsEnumerable() in C#

To cast a specific type to its IEnumerable equivalent, use the AsEnumerable() method. It is an extension method. int[] arr = new int[5], arr[0] = 10, arr[1] = 20, arr[2] = 30, arr[3] = 40, arr[4] = 50, Now, get the IEnumerable equivalent.

Is IEnumerable lazy loading?

IEnumerable doesn’t support lazy loading. IQueryable support lazy loading. Hence it is suitable for paging like scenarios.