How do I update an IEnumerable object?

How do I update an IEnumerable object?

5 Answers

1. Save the “new” collection back to the variable (or a new variable, if necessary): allsubdirs = allsubdirs. Select(a => a = a + “_” + DateTime.
2. Use a writable interface like IList and a for loop: IList allsubdirs = new List() { “a”, “b”, “c” }; for(int i=0; i

Is IEnumerable readonly?

8 Answers. In fact, IEnumerable is already readonly. It means you cannot replace any items in the underlying collection with different items. That is, you cannot alter the references to the Person objects that are held in the collection.

What is IEnumerable in C#?

IEnumerable in C# is an interface that defines one method, GetEnumerator which returns an IEnumerator interface. This allows readonly access to a collection then a collection that implements IEnumerable can be used with a for-each statement.

How do you use select many?

SelectMany() method For example, SelectMany() can turn a two-dimensional array into a single sequence of values, as shown in this example: int[][] arrays = { new[] {1, 2, 3}, new[] {4}, new[] {5, 6, 7, 8}, new[] {12, 14} }; // Will return { 1, 2, 3, 4, 5, 6, 7, 8, 12, 14 } IEnumerable result = arrays.

Should I use IEnumerable or list?

10 Answers. IEnumerable describes behavior, while List is an implementation of that behavior. When you use IEnumerable , you give the compiler a chance to defer work until later, possibly optimizing along the way. If you use ToList() you force the compiler to reify the results right away.

What is GetEnumerator C#?

The C# GetEnumerator() method is used to convert string object into char enumerator. It returns instance of CharEnumerator. So, you can iterate string through loop.

Is IEnumerable immutable?

Just realized IEnumerable is immutable, what are other most commonly used immutable generic interfaces? MSDN doesn’t say [closed] As it currently stands, this question is not a good fit for our Q&A format.

What does readonly do in C#?

The readonly modifier prevents the field from being replaced by a different instance of the reference type. However, the modifier doesn’t prevent the instance data of the field from being modified through the read-only field.

Why IEnumerable is used in C#?

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.

Is a list IEnumerable C#?

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 .

What is difference between Select and select many?

Select is used to select value from a collection whereas SelectMany is used to select values from a collection of collection i.e. nested collection. Select and SelectMany both are projection operators. In below example we will return a list of courses, each containing a list of subjects.

Does SelectMany remove duplicates?

// SelectMany will return all duplicates objects.

How to update an item in IEnumerable Stack Overflow?

Linq is for querying, not updating. For updating a single item, you can retrieve the index of the item to be updated and use that index to update it. If you don’t want to store it in another variable, consider using ToList ().

What is the use of IEnumerable in C #?

What is IEnumerable in C#? IEnumerable in C# is an interface that defines one method, GetEnumerator which returns an IEnumerator interface. This allows readonly access to a collection then a collection that implements IEnumerable can be used with a for-each statement.

What is the GetEnumerator method in IEnumerable?

In the above example, you have seen that after implementing the IEnumerable Interface there is method called GetEnumerator along with interface IEnumerator which helps to get current elements from the collection.

How to enumerate over generic collection in IEnumerable?

The Arraylist class is a generalized class that let us keep a collection. We can also have a generic class in which we can provide the type along with the data. Iterating over generic collection classes is also possible because they implement IEnumerable interface. Lets see how we can enumerate over a generic collection.