Using NULL Conditional Operator With Indexes

NULL conditional operator or NULL propagation operator was introduced with C# 6.0 and you will find dozens of blogs and articles on NULL conditional operator. I have also written some articles on it and following is a link for the same but I have noticed that very few people are using all the benefits of NULL conditional operator.

NULL Conditional Operator In C# 6.0

In this blog, I am going to present those hidden gems for you.

There are 2 syntaxes for NULL conditional operator, which are given below.

NULL conditional operator for member access (?.)
NULL conditional operator for index based access (?[)

So the first syntax “?.” is being used very popularly but the second syntax “?[” is used by very few people. But I am going to cover all those in this blog.

NULL conditional operator for member access (?.)

Have a look at the code snippet given below.

static void Main(string[] args)
{
string name = null;
int length = name.Length;
}

The preceding code snippet will throw an exception NullReferenceException.

If I use the NULL conditional operator (?.), then the preceding code snippet can be written as given below.

static void Main(string[] args)
{
string name = null;
int? length = name?.Length;
}

It will run successfully without throwing any exception.

NULL conditional operator for member access (?.) with null-coalescing operator (??)

if you do not want to make the length variable as Nullable int type, then you can use null-coalescing operator (??) with “?.” Follow the code snippet given below for the same.

static void Main(string[] args)
{
string name = null;
int length = name?.Length ?? 0;
}

More useful example with complete code is given below.

using static System.Console;
namespace NULLConditionalOperatorExample
{
class Program
{
static void Main(string[] args)
{
Customer cust = new Customer { Id=101};
WriteLine($"Customer id: {cust.Id} & name: {cust.Name??"N/A"}");
WriteLine($"Customer name contains {cust.Name?.Length ??0} character(s)");
}
}
class Customer
{
public int Id { get; set; }
public string Name { get; set; }
}
}

NULL conditional operator for index based access (?[)

Have a look at the code snippet given below.

static void Main(string[] args)
{
int[] Numbers = { 1, 2, 3, 4, 5 };
Numbers = null;
WriteLine($"5th element is: {Numbers[4]}");
}

The preceeding code snippet will throw an exception NullReferenceException.

If I use the NULL conditional operator (?[), then the preceeding code snippet can be written, as given below.

static void Main(string[] args)
{
int[] Numbers = { 1, 2, 3, 4, 5 };
Numbers = null;
WriteLine($"5th element is: {Numbers?[4]}");
}

It will run successfully without throwing any exception.

You can also learn about C# 7 by going through the links given below.

3 Comments

Join the conversation! Your thoughts help the community grow.

Bhavesh Jadav8y ago
Super explanation sir, it's new for me thanks for sharing it.
Rajesh Kadam9y ago
Very good explanation in very simple language.. thanks
- Banketeshvar Narayan9y ago
  Thanks Rajesh Kadam for your valuable feedback.