How to use List in C#? Summary of basic usage of List

　What about List in C#? The List<T> class is the generic equivalent of the ArrayList class, which implements the IList<T> generic interface using an array whose size can be dynamically increased as needed. Next, the editor will introduce some basic and simple usage of List.

Benefits of generics: It adds great efficiency and flexibility to writing object-oriented programs using the C# language. There is no forced boxing and unboxing of value types, or downcasting of reference types, so performance is improved.

Performance Note: When deciding to use IList<T> or the ArrayList class (both have similar functionality), remember that the IList<T> class performs better in most cases and is type-safe. If you use a reference type for type T of the IList<T> class, the behavior of the two classes is exactly the same. However, if you use a value type for type T, you need to consider implementation and boxing issues.

Basic common methods of C# List:

1. Statement:

1. List<T> mList = new List<T>();

T is the element type in the list, now take the string type as an example ：

　 List<string> mList = new List<string>();

　 2. List<T> testList =new List<T> (IEnumerable<T> collection);

Create a List with a collection as a parameter ：

　 string[] temArr = { "Ha", "Hunter", "Tom", "Lily", "Jay", "Jim", "Kuku", "Locu"};

　 List<string> testList = new List<string>(temArr);

　　2. Add elements:

　1. List. Add(T item) Add an element

　Example:

　mList.Add("John");

　2 , List. AddRange(IEnumerable<T> collection) adds a set of elements

Example:

　string[] temArr = {"Ha","Hunter","Tom","Lily","Jay","Jim" ,"Kuku","Locu"};mList.AddRange(temArr);

　3. Insert(intindex, T item); Add an element at the index position

　Example:

　mList.Insert(1,"Hei ");

3. Traverse the elements in the List:

foreach(TelementinmList)T的类型与mList声明时一样
{
Console.WriteLine(element);
}
例：
foreach(stringsinmList)
{
Console.WriteLine(s);
}

4. Delete elements:

1. List. Remove(T item) deletes a value

Example:

mList.Remove("Hunter ");

　 2. List. RemoveAt(intindex); Delete the element whose subscript is index

　 Example:

　 mList.RemoveAt(0);

3. List. RemoveRange(intindex,intcount);

Starting from the subscript index, delete count elements

Example:

mList.RemoveRange(3, 2);

5. Determine whether an element is in the List:

List. Contains(T item) Return true or false, very practical

Example:

if(mList.Contains("Hunter"))
{
Console.WriteLine("There is Hunter in the list");
}
else
{
mList.Add("Hunter");
Console.WriteLine("Add Hunter successfully.");
}

6. Sort the elements in the List:

List. Sort () defaults to the first letter of the element in ascending order

Example:

mList.Sort ();

7. Reverse the order of elements in List:

List. Reverse () can be used in conjunction with List. Sort () to achieve the desired effect

Example:

mList.Sort();

8. Clear the List:

List. Clear ()

Example:

mList.Clear(); Example:
N in tcount = mlist.count ();

console.writeline ("the num of elements in the list:"+count); You guys are helpful.

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