C# 6.0 and 7.x posts links

Hello All,

There are rapid changes to C# language recently. Although these are very useful in writing cleaner, concise, less repetitive and performance oriented code, I see very less usage of these in our day to day coding. So I thought of writing these features as blog posts to learn myself and share with others. In this post I am just listing down the links of my earlier C#6.0 and C# 7.x blog posts so that it is easily available. Do let me know if there is any important feature that I missed which could be useful in our day to day coding.

C# 6.0 features

C# 7.X features

Hope you’ll enjoy these posts and able to use these in your day to day development.

Cheers,
Brij

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Expression-bodied Members in C#

Expression-bodied members are one of the shiny features of C# 6.0 which allows us to write the implementation of a member in more readable and concise format. We can use the expressions as a definition of the members instead of using the statement block. The format of the expression is as

var=> expression

This is also called lambda expressions and => is called lambda operator. In C# 6.0, we can use this feature with methods and properties. Lets see few examples

Properties: Instead of using the normal getter, we can use expressions with lambda operators as mentioned.


// Normal way
public string FullName
{
    get { return string.Format("{0} {1}", FirstName, LastName); }
}

// Using Expression (C# 6.0)
public string FullName => string.Format("{0} {1}", FirstName, LastName);

// Above code can be more consize using string interpolation
public string FullName =>$"{FirstName} {LastName}";

If you are not aware of String Interpolation, you can refer one of my previous post here.

Methods : Similar to properties, C# 6.0 also allows us to use expressions while writing methods which returns values to the caller.


// Normal way
public string GetFullName(string firstname, string middleName, string lastName)
{
    return middleName == null ? $"{firstname} {lastName}" : $"{firstname} {middleName} {lastName}";
}

// Using Expessions 
public string GetFullName(string firstname, string middleName, string lastName) => middleName == null ? 
             $"{firstname} {lastName}" : $"{firstname} {middleName} {lastName}";

Limitation: There is a limitation of expression bodied members.We can have just single statement in the expression and statement blocks {} are not allowed. In my above example, I used the ternary operator conditional logic instead of using if statement block.

As we can see C# 6.0 added the capability for methods and read only properties, C# 7.0 added more power to this feature and now we can use expressions in constructors, set accessors in properties, indexers and finalizers. Let’s take a look

Properties: We saw earlier enhancements for Property which was similar to get accessor

private string _name;
public string Name {
    get => _name;
    set => _name = value;
}

Here this is a very simple example and in this scenario, I would like to prefer the Auto propery as below

public string Name { get; set; }

However in my earlier example where I was returning FullName after concatenating two strings, there it is better suited. So when you are doing some smaller operations as well in your property then it is better choice.

Constructor: We can leverage the expression with the constructors as well. Let’s see

// Earlier
public Person(string name)
{
    this.Name = name;
}

// With C# 7.0
public Person(string name) => this.Name = name; 

As mentioned earlier that statement block can’t be used here. So say if I have multiple parameters to pass so I can use another C# 7.0 features: ValueTuple and Destructors.

public Person(string firstName, string lastName) => (FirstName, LastName) = (firstName, lastName);

I wrote some time back on ValueTuples and Deconstructors, you can take a look.

Finalizers: We can use expressions in finalizers as well. Let’s see

// Earlier
~Person()
{
    Console.WriteLine("Person's destructor");
}

// Using Expressions
~Person() => Console.WriteLine("Person's destructor");

There are many new features that got intrudocuced in C# 6.0 and C# 7.X (7.0, 7.1, 7.2) if these are used together, can provide lot of value. The whole idea is write cleaner, concise and more performant code so that the focus is more on business logic.

Hope you are enjoying the enhancements.

Cheers
Brij

How to use Null Conditional operators

Null values are very special in any language, specifically in C#. Every .NET developer must have pulled his/her hair at some point or other while dealing with it. C# is getting mature by adding more capabilities to handle the null values so that we don’t need to write long repetitive code to handle it. This operator was introduced with C# 6.0 sometimes also referred as safe navigation operator, and can be panacea for the most common NullReferenceException. There are few related topics like Null Coalescing operator, Nullable types, which I will advise to take a quick look before proceeding.

What is Null Conditional Operator?

This is a new operator introduced with C# 6.0, helps in performing null check while accessing its members. It provides following two syntax

  1. First operator: ?.   (Also called elvis operator)
  2. Second operator: ?[

Let’s see it with examples

First Null Conditional Operator (?.):

This operator allows us to access the members or elements of the provided instance only when it is not null. So before moving further, lets create few classes for the example

public class Person
{
    public string FirstName { get; set; }

    public string LastName { get; set; }

    public int Age { get; set; }

    public List <Address> Addresses { get; set;}

    public Person Spouse {get; set;}
}

public class Address
{
    public string Address1 { get; set; }
    public string Address2 { get; set; }

    public string City { get; set; }

    public string State { get; set; }

    public string Zip { get; set; }
}

If you have to access properties of the person, the usual way of doing it

if(p != null)
{
    string name = p.FirstName;
    int age = p.Age;
}

Now lets see using the ?. operator

string name = p?.FirstName;
int? age = p?.Age;

Here we dont need to have a null check as it is taken care by the null conditional operator. name is assigned to null if either object p is null or FirstName is null. While for age, I had to change the age variable as Nullable type because for value types, this operator returns a nullable type which is easily understandable as it would have no value (or null) if p is null.

Now if want to access the properties of Spouse then normally code would be as

if(p != null && p.Spouse != null)
{
    string name = p.Spouse.FirstName;
    int age = p.Spouse.Age;
}

which can be written as

string name = p?.Spouse?.FirstName;
int? Age = p?.Spouse?.Age;

Here, we avoided two null check and code looks much cleaner and concise. This operators becomes more helpful for the descending types. You must have written similar code like below numerous times while handling a service response

if (response != null && response.Results != null && response.Results.Status == Status.Success)
{
    // Handle response
}

this can be as

if (response?.Results?.Status == Status.Success)
{
        // Handle response
}

It looks super clean now. It could be more granular based on the scenario. Now let’s see another operator.

Second Null Conditional Operator (?[): This operator allows you to have a check over index operator. Let’s see the example.
Here I want to see the city of the second address of the person so normally, we will write it as

if(p!=null && p.Addresses != null && p.Addresses.Count > 1)
{
    string city = p.Addresses[1].City;
}

This we can write now as

string city = p?.Addresses?[1]?.City;

Now you can assume if I have read the same for spouse then how consize code would be.

Other Usages:
It can be used while calling method of instance like

p?.ToString();

We can use it with delegate and events as well like

myCustomDelegate?.Invoke(args)

// Note : myCustomDelegate?(args) won't work and it will be an compile time error

myCustomEvent?.Invoke(this, args);

I found this feature very useful in our day to day coding as we save lot of repetitive code. Hope you find it useful as well.

Cheers,
Brij