The List<'T> class represents a strongly typed list of objects that index can access. It is a mutable counterpart of the List class.
List<'T> class similar to arrays, but unlike arrays, lists can be resized and don't need to have their size specified on the declaration.new keyword.The following example creates a list by calling its constructor, as shown below.
let myList = new List<string>()
myList.Add("one")
myList.Add("two")
myList.Add("three")
myList |> Seq.iteri (fun index item -> Console.WriteLine("{0}: {1}", index, myList.[index]))
The List<'T> class is just a fancy wrapper for an array.
List<'T> is constructed, it creates a 4-element array in memory.O(1) operation.O(n) operation, where n is the number of items in the list.The following are the most commonly used functions in the List<'T> class.
| Function | Description |
|---|---|
| Add | Adds an object to the end of the list. |
| AddRange | Adds the elements of the specified collection to the end of the list. |
| Clear | Removes all elements from the list. |
| Contains | Determines whether an element is in the list. |
| ConvertAll | Converts the elements in the current list to another type, and returns a list containing the converted elements. |
| CopyTo | Copies the entire list to a compatible one-dimensional array, starting at the beginning of the target array. |
| Equals | Determines whether the specified object is equal to the current object. |
| Exists | Determines whether the list contains elements that match the conditions defined by the specified predicate. |
| Find | Searches for an element that matches the conditions defined by the specified predicate and returns the entire list's first occurrence. |
| FindAll | Retrieves all the elements that match the conditions defined by the specified predicate. |
| ForEach | Performs the specified action on each element of the list. |
| IndexOf | Searches for the specified object and returns the zero-based index of the first occurrence within the entire list. |
| Insert | Inserts an element into the list at the specified index. |
| InsertRange | Inserts the elements of a collection into the list at the specified index. |
| Remove | Removes the first occurrence of a specific object from the list. |
| 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. |
| RemoveRange | Removes a range of elements from the list. |
| Reverse | Reverses the order of the elements in the entire list. |
| Sort | Sorts the elements in the entire list using the default comparer. |
| ToArray | Copies the elements of the list to a new array. |
| ToString | Returns a string that represents the current object. |
The following example uses some of these functions.
let months = new List<string>()
months.Add("January")
months.Add("February")
//months.Add("March")
months.Add("April")
months.Add("May")
months.Add("June")
months.Add("July")
months.Add("August")
months.Add("September")
months.Add("October")
months.Add("November")
months.Add("December")
printfn"Total %d months" months.Count
months |> Seq.iteri (fun index item -> printfn "%i: %s" index months.[index])
months.Insert(2, "March")
printfn("after inserting at index 2")
printfn"Total %d months" months.Count
months |> Seq.iteri (fun index item -> printfn "%i: %s" index months.[index])
months.RemoveAt(3)
printfn("after removing from index 3")
printfn"Total %d months" months.Count
months |> Seq.iteri (fun index item -> printfn "%i: %s" index months.[index])