C# Array - CreateInstance() Method

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The C# Array CreateInstance() method is used to create new instance of an array with a specified type, dimensions, and lengths for each dimension.

The array that is created may have one or multiple dimensions, depending on the length that is given.

This method is especially useful when the type or dimensions of the array are not known at compile time.

Exception

There are the following exceptions of CreateInstance() methods −

• ArgumentNullException: Thrown if the elementType is null.
• ArgumentOutOfRangeException: Thrown if any of the dimensions are less than zero
• ArgumentException: Thrown if the elementType is invalid

Syntax

Following is the syntax of the C# Array CreateInstance() method −

public static Array CreateInstance (Type elementType, int length);

Parameters

This method accepts the following parameters −

• elementType: Specifies the type of the array's elements.
• length: Specifies the size of array in each dimension.

Return value

This method returns an instance of the array class.

Example 1: Create a One-Dimensional Array

This is the basic example of theCreateInstance()method to create an instance of one-dimensional array −

using System;
class Program
{
   static void Main()
   {
      // use CreateInstance method
      Array array = Array.CreateInstance(typeof(int), 5);
	  
      for (int i = 0; i < array.Length; i++)
      {
          array.SetValue(i * 10, i);
      }
	  
      foreach (var item in array)
      {
          Console.Write(item + " ");
      }
   }
}

Output

Following is the output −

0 10 20 30 40

Example 2: Create Multi-Dimensional Array

Let us see another example of the CreateInstance() method to create an instance of multi-dimensional array −

using System;
class Program
{
   static void Main()
   {
      Array array = Array.CreateInstance(typeof(int), 3, 2);

      // Fill the array with values
      for (int i = 0; i < 3; i++)
      {
         for (int j = 0; j < 2; j++)
         {
            array.SetValue((i + 1) * (j + 1), i, j);
         }
      }
      // Print the array
      for (int i = 0; i < 3; i++)
      {
         for (int j = 0; j < 2; j++)
         {
            Console.Write(array.GetValue(i, j) + " ");
         }
         Console.WriteLine();
      }
   }
}

Output

Following is the output −

1 2 
2 4 
3 6

Example 3: Create an Array of String

In this example of the CreateInstance() method. We create an instance of one-dimensional string array −

using System;
class Program
{
   static void Main()
   {
      // Create a one-dimensional array of strings
      Array stringArray = Array.CreateInstance(typeof(string), 4);

      stringArray.SetValue("Apple", 0);
      stringArray.SetValue("Banana", 1);
      stringArray.SetValue("Cherry", 2);
      stringArray.SetValue("Date", 3);

      foreach (var item in stringArray)
      {
         Console.Write(item + " ");
      }
   }
}

Output

Following is the output −

Apple Banana Cherry Date 

Example 4: Handling Invalid Dimension

Following is another example of theCreateInstance()method. Here, we are attempting to create an array with a negative dimension −

using System;
class Program
{
   static void Main()
   {
      try
      {
         // Attempt to create an array with a negative dimension
         Array array = Array.CreateInstance(typeof(int), -5);
      }
      catch (Exception ex)
      {
         Console.WriteLine($"Exception: {ex.Message}");
      }
   }
}

Output

Following is the output −

Exception: MonoArgumentException:NULL