Cast Operator

Back to: LINQ Tutorial For Beginners and Professionals

Cast Operator in C# with Examples:

In this article, I am going to discuss the Cast Operator in C# with some examples. Please read our previous article before proceeding to this article where we discussed the ToDictionary Method in C# with some examples. Like ToList, ToArray, ToDictionary, the Cast Operator also belongs to the conversion operators category.

Cast Operator in C#:

The Cast Operator in C# is used to casts all the elements of a collection (System.Collections.IEnumerable) to a specified type and then return a new System.Collections.Generic.IEnumerable<T> collection which contains all the elements of the source sequence cast to the specified type. This method uses deferred execution.

The signature of this method is given below.

Parameters:

1. source: The System.Collections.IEnumerable that contains the elements to be cast to type TResult.

Type parameters:

1. TResult: The type to cast the elements of source.

Exceptions: It will throw System.ArgumentNullException when the source is null.  It also throws System.InvalidCastException when an element in the source sequence cannot be cast to the specified type TResult.

Example:

In the following example, the source sequence contains 3 elements and all these three elements are of type integer. So, all these elements are cast to integers.

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

namespace ConversionOperators
{
    class Program
    {
        public static void Main()
        {
            ArrayList list = new ArrayList
            {
                10,
                20,
                30
            };

            IEnumerable<int> result = list.Cast<int>();

            foreach (int i in result)
            {
                Console.WriteLine(i);
            }

            Console.ReadKey();
        }
    }
}

Output: 10 20 30

Example2:

In the following example, the line “list.Add(“40”);” will throw an exception. This is because it is a string value and we are trying to convert it into an int. So, it will throw System.InvalidCastException.

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

namespace ConversionOperators
{
    class Program
    {
        public static void Main()
        {
            ArrayList list = new ArrayList
            {
                10,
                20,
                30,
            };

            //The following statement throws System.InvalidCastException
            list.Add("40");

            IEnumerable<int> result = list.Cast<int>();

            foreach (int i in result)
            {
                Console.WriteLine(i);
            }

            Console.ReadKey();
        }
    }
}

Example3:

In the following example, the source sequence is null. So, when we run the application, it will throw System.ArgumentNullException.

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

namespace ConversionOperators
{
    class Program
    {
        public static void Main()
        {
            ArrayList list = null;

            //Throws System.ArgumentNullException
            IEnumerable<int> result = list.Cast<int>();

            foreach (int i in result)
            {
                Console.WriteLine(i);
            }

            Console.ReadKey();
        }
    }
}

In the next article, I am going to discuss the differences between Cast and OfType operators in C# with an example. Here, in this article, I try to explain the need and use of Cast Operator in C# with some examples. I hope you understood the need and use of Cast Operator.