C#| How to change the size of one-dimensional array

Array.Resize(T[], Int32) Method is used to resize the number of elements present in the array. Or in other words, this method is used to change the number of elements of a one-dimensional array to the specified new size. It resizes the only 1-D array, not multidimensional array.

Syntax:

public static void Resize<T> (ref T[] array, int newSize);

Parameters:

array: It is a one-dimensional, zero-based array to resize, or null to create a new array with the specified size.
newsize: It is the size of the new array.

Exception:If the value of nsize is less than zero, then this method will give ArgumentOutOfRangeException.

Note: This method is an O(n) operation, where n is new size.

Below given are some examples to understand the implementation in a better way:

Example 1:

// C# program to resize the
// elements of the 1-D array
using System;

public class GFG {

    // Main method
    static public void Main()
    {

        // create and initialize array
        string[] myarray = {"C#", "Java", "C++", "Python",
                             "HTML", "CSS", "JavaScript"};

        // Display original array before Resize
        Console.WriteLine("Original Array:");

        foreach(string i in myarray)
        {
            Console.WriteLine(i);
        }

        int len = myarray.Length;
        Console.WriteLine("Length of myarray: "+len);
        Console.WriteLine();

        // Resize the element of myarray and
        // create a new array. Here new array
        // is smaller than the original array
        // so, elements are copied from the
        // myarray to the new array until the
        // new one is filled. The rest of the
        // elements in the old array are ignored
        Array.Resize(ref myarray, len - 3);

        Console.WriteLine("New array is less than myarray:");

        foreach(string j in myarray)
        {
            Console.WriteLine(j);
        }

    }
}

Output:

Original Array:
C#
Java
C++
Python
HTML
CSS
JavaScript
Length of myarray: 7

New array is less than myarray:
C#
Java
C++
Python

Example 2:

// C# program to resize the
// elements of the 1-D array
using System;

public class GFG {

    // Main method
    static public void Main()
    {

        // create and initialize array
        string[] myarray = {"C#", "C++", "Ruby",
                         "Java", "PHP", "Perl"};

        // Display original string before Resize
        Console.WriteLine("Original Array:");

        foreach(string i in myarray)
        {
            Console.WriteLine(i);
        }

        // Length of old array
        int len = myarray.Length;
        Console.WriteLine("Length of myarray: "+len);
        Console.WriteLine();

        // Resize the element of myarray
        // and create a new array
        // Here new array is greater than
        // original array so, all the element
        // from myarray is copied to new array
        // and remaining will be null
        Array.Resize(ref myarray, 10);

        Console.WriteLine("New array is greater than myarray:");

        foreach(string j in myarray)
        {
            Console.WriteLine(j);
        }

        // Length of new array
        int len1 = myarray.Length;
        Console.WriteLine("Length of New Array: "+len1);

    }
}

Output:

Original Array:
C#
C++
Ruby
Java
PHP
Perl
Length of myarray: 6

New array is greater than myarray:
C#
C++
Ruby
Java
PHP
Perl




Length of New Array: 10

Reference: https://docs.microsoft.com/en-us/dotnet/api/system.array.resize?view=netcore-2.1