How to Add String to an Array in C#

1. Add String to Array With the List.Add() Method in C#
2. Add String to Array With the Array.Resize() Method in C#

This tutorial will discuss methods to add new strings to a wholly filled array in C#.

Add String to Array With the List.Add() Method in C#

Unfortunately, there is no built-in method for adding new values to an array in C#. The List data structure should be used for dynamic allocation and de-allocation of values in C#. But, if we have a filled array containing some important data and want to add a new element to the array, we can follow the following procedure. The Linq is used to integrate query functionality of the SQL on data structures in C#. We can use the ToList() method of Linq to convert our array to a list and then add values to the list with the List.Add() method in C#. In the end, we can convert the list back to our array with the List.ToArray() method. The following code example shows us how we can add a new element to a completely filled array with the List.Add() method in C#.

using System;
using System.Collections.Generic;
using System.Linq;

namespace Array_Add {
  class Program {
    static void Main(string[] args) {
      string[] arr = { "One", "Two", "Three" };
      string newElement = "New Element";
      List<string> list = new List<string>(arr.ToList());
      list.Add(newElement);
      arr = list.ToArray();
      foreach (var e in arr) {
        Console.WriteLine(e);
      }
    }
  }
}

Output:

One
Two
Three
New Element

We initialized the array of strings arr and the string variable newElement in the above code. We converted the arr array to the list list with the arr.ToList() method. We then added the newElement to the list with the list.Add(newElement) method. In the end, we converted the list list back to the arr array with the list.ToArray() method in C#.

Add String to Array With the Array.Resize() Method in C#

We can also use the following to add a new element to a completely filled array in C#. The Array.Resize() method changes the number of elements of a one-dimensional array in C#. The Array.Resize() method takes a reference to the array and its new length as parameters and resizes that array. We can increase our array size by one element each time we have to add a new element to it. The following code example shows us how to add a new element to a completely filled array with the Array.Resize() method in C#.

using System;
using System.Collections.Generic;

namespace Array_Add {
  class Program {
    static void Main(string[] args) {
      string[] arr = { "One", "Two", "Three" };
      string newElement = "New Element";
      Array.Resize(ref arr, arr.Length + 1);
      arr[arr.Length - 1] = newElement;
      foreach (var e in arr) {
        Console.WriteLine(e);
      }
    }
  }
}

Output:

One
Two
Three
New Element

We initialized the array of strings arr and the newElement string in the above code. We increased the size of the arr array by one element with the Array.Resize() function and assigned newElement to the last index of the arr array.