F Sharp Mutable Lists - F Sharp (programming language)

What is F# - Mutable Lists?

The List<'T> class represents a strongly typed list of objects that can be accessed by index.

It is a mutable counterpart of the List class. It is similar to arrays, as it can be accessed by an index, however, unlike arrays, lists can be resized. Therefore you need not specify a size during declaration.

Creating a Mutable List

Lists are created using the new keyword and calling the list's constructor. The following example demonstrates this −

When you compile and execute the program, it yields the following output −

The List(T) Class

The List(T) class represents a strongly typed list of objects that can be accessed by index. It provide methods to search, sort, and manipulate lists.

The following tables provide the properties, constructors and the methods of the List(T) class −

Properties

Property

Description

Capacity

Gets or sets the total number of elements the internal data structure can hold without resizing.

Count

Gets the number of elements contained in the List(T).

Item

Gets or sets the element at the specified index.

Constructors

Constructor

Description

List(T)()

Initializes a new instance of the List(T) class that is empty and has the default initial capacity.

List(T)(IEnumerable(T))

Initializes a new instance of the List(T) class that contains elements copied from the specified collection and has sufficient capacity to accommodate the number of elements copied.

List(T)(Int32)

Initializes a new instance of the List(T) class that is empty and has the specified initial capacity.

Method

Methods

Description

Add

Adds an object to the end of the List(T).

AddRange

Adds the elements of the specified collection to the end of the List(T).

AsReadOnly

Returns a read-only IList(T) wrapper for the current collection.

BinarySearch(T)

Searches the entire sorted List(T) for an element using the default comparer and returns the zero-based index of the element.

BinarySearch(T, IComparer(T))

Searches the entire sorted List(T) for an element using the specified comparer and returns the zero-based index of the element.

BinarySearch(Int32, Int32, T, IComparer(T))

Searches a range of elements in the sorted List(T) for an element using the specified comparer and returns the zero-based index of the element.

Clear

Removes all elements from the List(T).

Contains

Determines whether an element is in the List(T).

ConvertAll(TOutput)

Converts the elements in the current List(T) to another type, and returns a list containing the converted elements.

CopyTo(T[])

Copies the entire List(T) to a compatible one-dimensional array, starting at the beginning of the target array.

CopyTo(T[], Int32)

Copies the entire List(T) to a compatible one-dimensional array, starting at the specified index of the target array.

CopyTo(Int32, T[], Int32, Int32)

Copies a range of elements from the List(T) to a compatible one-dimensional array, starting at the specified index of the target array.

Equals(Object)

Determines whether the specified object is equal to the current object. (Inherited from Object.)

Exists

Determines whether the List(T) contains elements that match the conditions defined by the specified predicate.

Finalize

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection (Inherited from Object).

Find

Searches for an element that matches the conditions defined by the specified predicate, and returns the first occurrence within the entire List(T).

FindAll

Retrieves all the elements that match the conditions defined by the specified predicate.

FindIndex(Predicate(T))

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the entire List(T).

FindIndex(Int32, Predicate(T))

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the List(T) that extends from the specified index to the last element.

FindIndex(Int32, Int32, Predicate(T))

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the List(T) that starts at the specified index and contains the specified number of elements.

FindLast

Searches for an element that matches the conditions defined by the specified predicate, and returns the last occurrence within the entire List(T).

FindLastIndex(Predicate(T))

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the entire List(T).

FindLastIndex(Int32, Predicate(T))

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the List(T) that extends from the first element to the specified index.

FindLastIndex(Int32, Int32, Predicate(T))

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the List(T) that contains the specified number of elements and ends at the specified index.

ForEach

Performs the specified action on each element of the List(T).

GetEnumerator

Returns an enumerator that iterates through the List(T).

GetHashCode

Serves as the default hash function. (Inherited from Object.)

GetRange

Creates a shallow copy of a range of elements in the source List(T).

GetType

Gets the Type of the current instance. (Inherited from Object.)

IndexOf(T)

Searches for the specified object and returns the zero-based index of the first occurrence within the entire List(T).

IndexOf(T, Int32)

Searches for the specified object and returns the zero-based index of the first occurrence within the range of elements in the List(T) that extends from the specified index to the last element.

IndexOf(T, Int32, Int32)

Searches for the specified object and returns the zero-based index of the first occurrence within the range of elements in the List(T) that starts at the specified index and contains the specified number of elements.

Insert

Inserts an element into the List(T) at the specified index.

InsertRange

Inserts the elements of a collection into the List(T) at the specified index.

LastIndexOf(T)

Searches for the specified object and returns the zero-based index of the last occurrence within the entire List(T).

LastIndexOf(T, Int32)

Searches for the specified object and returns the zero-based index of the last occurrence within the range of elements in the List(T) that extends from the first element to the specified index.

LastIndexOf(T, Int32, Int32)

Searches for the specified object and returns the zero-based index of the last occurrence within the range of elements in the List(T) that contains the specified number of elements and ends at the specified index.

MemberwiseClone

Creates a shallow copy of the current Object. (Inherited from Object.)

Remove

Removes the first occurrence of a specific object from the List(T).

RemoveAll

Removes all the elements that match the conditions defined by the specified predicate.

RemoveAt

Removes the element at the specified index of the List(T).

RemoveRange

Removes a range of elements from the List(T).

Reverse()

Reverses the order of the elements in the entire List(T).

Reverse(Int32, Int32)

Reverses the order of the elements in the specified range.

Sort()

Sorts the elements in the entire List(T) using the default comparer.

Sort(Comparison(T))

Sorts the elements in the entire List(T) using the specified System. Comparison(T).

Sort(IComparer(T))

Sorts the elements in the entire List(T) using the specified comparer.

Sort(Int32, Int32, IComparer(T))

Sorts the elements in a range of elements in List(T) using the specified comparer.

ToArray

Copies the elements of the List(T) to a new array.

ToString

Returns a string that represents the current object. (Inherited from Object.)

TrimExcess

Sets the capacity to the actual number of elements in the List(T), if that number is less than a threshold value.

TrueForAll

Determines whether every element in the List(T) matches the conditions defined by the specified predicate.

Example

On compiling and and executing the program, it produces the below result

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