A list is a set of index-accessible objects that provides functionality for searching, sorting, and manipulating list items. C# List class represents a collection of strongly typed objects that can be accessed by using the index. In this article, we learn how to work with lists in C# using the C# List class to add, remove, and search items in a collection of objects using List class methods and properties.
\nList<T> class in C# cotains a strongly typed list of objects. It provides functionality to create a list of objects, add list items, search, sort and manipulate list items. In List<T>, T is the type of objects like int, string, or any user-defined object.
List<T> is required when we have multiple items with the same object, like data of student's marks or data of various subject's names (string). In that case, we can use List<T> to maintain that data into a list.
List<T> comes under the System.Collection.Generic namespace and the index start from 0.
We can create a list by calling the List<T> constructor; It takes an argument of int type that is the list's capacity. If we do not define the capacity, then the list size will be dynamic and every time an element is added, the list size is increased. The list can be created using the below syntax.
List<int> lst=new List<int>(); // list with dynamic capacity\nList<int> lstCapacity=new List<int>(10); // list with capacity of 10 elementsAs we have discussed above, Here T is the type of object for which we have to create the list. The type is int in the above code, which means we can store the int type of variable's value.
Note: If we have created the list using the capacity value and when more than the defined capacity elements are added, the list size will automatically increase.
\nWe can add elements directly into when we have created a list or add elements after creating a list. I will discuss both methods here.
\nList<int> lst = new List<int>\n{\n 1,2,3,4,5,6\n};List<int> lst = new List<int>();\nlst.Add(1);\nlst.Add(2);\nlst.Add(3);\nlst.Add(4);\nlst.Add(5);\nlst.Add(3);The list has mainly two properties.
\nList<int> lst = new List<int>();\nConsole.WriteLine(lst.Capacity); //Prints 0-- Default\nList<int> lst1 = new List<int>(5);\nConsole.WriteLine(lst1.Capacity); // Prints 5List<int> lst = new List<int>(5);\nConsole.WriteLine(lst.Count); // Prints 0\nlst.Add(1);\nlst.Add(2);\nConsole.WriteLine(lst.Count); //Prints 2To get all the elements of a list, we have to loop through the list. We can use for or foreach loop to get the elements. Below is the code to get all the elements using both the loops and print the element's values.
\n\nforeach (var item in lst)\n{\n Console.WriteLine(item);\n}In this method, we have to run the loop till the last element of the list. For that, I have used the Count property of the list
\nfor (int i = 0; i < lst.Count; i++)\n{\n Console.WriteLine(lst[i]);\n}Both the methods will give the same output. I am taking the above list example so the result will be
\nOutput:
\n1\n2\n3\n4\n5\n3To remove items from a list, we can use various list methods.
\nlst.Remove(3); // Removes the fist occurance of element 3Predicate<T> match)- This method removes all elements from a list that matches the condition defined by the specified predicate. We have to pass the predicate as a parameter.lst.RemoveAll(x=>x==3); // Removes all the elements 3lst.RemoveAt(0); // Removes 0th index element from a listlst.RemoveRange(0,2); // Removes element 1,2 because the starting index is 0 and count is 2lst.Clear(); // Removes all elements from a listIn this article, we have discussed the basics of List<T>, properties, and some methods. The main advantage of using the list is that it is faster and it is more friendly because it gives us many inbuilt methods to use and do the manipulation according to ourselves. If you want to learn more about C# here is an article written by me on How to Work with Nullable Types in C#