C# 1.0
C# 1.0 was released in 2002 and included all the important features of a statically typed object-
oriented modern language, as you will see throughout chapters 2 to 6.
C# 2.0
C# 2.0 was released in 2005 and focused on enabling strong data typing using generics,
to improve code performance and reduce type errors, including the topics listed in the
following table:
Feature Chapter Topic
Nullable value types 2 Making a value type nullable
Generics 6 Making types more reusable with generics
C# 3.0
C# 3.0 was released in 2007 and focused on enabling declarative coding with Language
INtegrated Queries (LINQ) and related features like anonymous types and lambda
expressions, including the topics listed in the following table:
Feature Chapter Topic
Implicitly typed local variables 2 Inferring the type of a local variable
LINQ 12 All topics in Chapter 12, Querying and Manipulating
Data Using LINQ
C# 4.0
C# 4.0 was released in 2010 and focused on improving interoperability with dynamic languages
like F# and Python, including the topics listed in the following table:
Feature Chapter Topic
Dynamic types 2 The dynamic type
Named/optional arguments 5 Optional parameters and named arguments
C# 5.0
C# 5.0 was released in 2012 and focused on simplifying asynchronous operation support
by automatically implementing complex state machines while writing what looks like
synchronous statements, including the topics listed in the following table:
Feature Chapter Topic
Simplified asynchronous tasks 13 Understanding async and await
C# 6.0
C# 6.0 was released in 2015 and focused on minor refinements to the language, including the
topics listed in the following table:
Feature Chapter Topic
Static imports 2 Simplifying the usage of the console
Interpolated strings 2 Displaying output to the user
Expression bodied members 5 Defining read-only properties
C# 7.0
C# 7.0 was released in March 2017 and focused on adding functional language features like
tuples and pattern matching, as well as minor refinements to the language, including the topics
listed in the following table:
Feature Chapter Topic
Binary literals and digit separators 2 Storing whole numbers
Pattern matching 3 Pattern matching with the if statement
out variables 5 Controlling how parameters are passed
Tuples 5 Combining multiple values with tuples
Local functions 6 Defining local functions
C# 7.1
C# 7.1 was released in August 2017 and focused on minor refinements to the language,
including the topics listed in the following table:
Feature Chapter Topic
Default literal expressions 5 Setting fields with default literal
Inferred tuple element names 5 Inferring tuple names
async Main 13 Improving responsiveness for console apps
C# 7.2
C# 7.2 was released in November 2017 and focused on minor refinements to the language,
including the topics listed in the following table:
Feature Chapter Topic
Leading underscores in numeric literals 2 Storing whole numbers
Non-trailing named arguments 5 Optional parameters and named arguments
private protected access modifier 5 Understanding access modifiers
You can test == and != with tuple types 5 Comparing tuples
C# 7.3
C# 7.3 was released in May 2018 and focused on performance-oriented safe code that improves
ref variables, pointers, and stackalloc. These are advanced and rarely needed for most
developers, so they are not covered in this book.
C# 8.0
C# 8.0 was released in September 2019 and focused on a major change to the language related
to null handling, including the topics listed in the following table:
Feature Chapter Topic
Nullable reference types 2 Making a reference type nullable
Switch expressions 3 Simplifying switch statements with switch expressions
Default interface methods 6 Understanding default interface methods
C# 9.0
C# 9.0 was released in November 2020 and focused on record types, refinements to pattern
matching, and minimal-code console apps, including the topics listed in the following table:
Feature Chapter Topic
Minimal-code console apps 1 Top-level programs
Enhanced pattern matching 5 Pattern matching with objects
Records 5 Working with records