C Sharp Language Features

C# 1

• Classes
• Structs
• Interfaces
• Events
• Properties
• Delegates
• Operators and expressions
• Statements
• Attributes

C# 2

• Generics
• Partial types
• Anonymous methods
• Nullable value types
• Iterators
• Covariance and contravariance

C# 3

• Auto-implemented properties
• Anonymous types
• Query expressions
• Lambda expressions
• Expression trees
• Extension methods
• Implicitly typed local variables
• Partial methods
• Object and collection initializers

C# 4

• Dynamic binding
• Named/optional arguments
• Generic covariant and contravariant
• Embedded interop types

C# 5

• Asynchronous members
• Caller info attributes

C# 6

• Static imports
• Exception filters
• Auto-property initializers
• Expression bodied members
• Null propagator
• String interpolation
• nameof operator
• Index initializers

C# 7.0

• Out variables
• Tuples and deconstruction
• Pattern matching
• Local functions
• Expanded expression bodied members
• Ref locals and returns

Other features included:

• Discards
• Binary Literals and Digit Separators
• Throw expressions

C# 7.1

• async Main method
• default literal expressions
• Inferred tuple element names
• Pattern matching on generic type parameters

C# 7.2

• Techniques for writing safe efficient code
• Non-trailing named arguments
• Leading underscores in numeric literals
• private protected access modifier
• Conditional ref expressions

C# 7.3

The following new features support the theme of better performance for safe code:

• You can access fixed fields without pinning.
• You can reassign ref local variables.
• You can use initializers on stackalloc arrays.
• You can use fixed statements with any type that supports a pattern.
• You can use additional generic constraints.

The following enhancements were made to existing features:

• You can test == and != with tuple types.
• You can use expression variables in more locations.
• You may attach attributes to the backing field of auto-implemented properties.
• Method resolution when arguments differ by in has been improved.
• Overload resolution now has fewer ambiguous cases.

The new compiler options are:

• -publicsign to enable Open Source Software (OSS) signing of assemblies.
• -pathmap to provide a mapping for source directories.

C# 8

• Readonly members
• Default interface methods
• Pattern matching enhancements:
  • Switch expressions
  • Property patterns
  • Tuple patterns
  • Positional patterns
• Using declarations
• Static local functions
• Disposable ref structs
• Nullable reference types
• Asynchronous streams
• Indices and ranges
• Null-coalescing assignment
• Unmanaged constructed types
• Stackalloc in nested expressions
• Enhancement of interpolated verbatim strings

C# 9

Not yet released