1. .NET and .NET Core
5.2 Type Operations
Pan Wuming
2016

2. Topics Elementary Types Casting and Type Conversions
Boxing and Unboxing
Implicit Types
Anonymous Types
Nullable types
Dynamic
as and is Operators
Three new languages: C#, IL and F#
Evolving from OO Paradigm
Everything is object
Members for Abstraction
Accessibility for Encapsulation
Inheritance and Polymorphism
Solving name confliction and multi-inheritance
Towards higher order: Expressiveness
Delegate
Lambda Expression
Generic
Attribute
LINQ
Compiler API
Effective coding
References：
Types (C# Programming Guide)（MSDN）

3. Types, Variables, and Values
C# is a strongly-typed language.
The information stored in a type can include the following
The storage space that a variable of the type requires.
The maximum and minimum values that it can represent.
The members (methods, fields, events, and so on) that it contains.
The base type it inherits from.
The location where the memory for variables will be allocated at run time.
The kinds of operations that are permitted.

4. Built-in Types Integers: byte, int…
Floating point values: float, double…
Boolean expressions: bool
Text characters: char
Decimal values: decimal
String: string
Object
Array

5. Strings A string is an object of type String whose value is text.
Internally, the text is stored as a sequential read-only collection of Char objects.
A C# string can contain any number of embedded null characters ('\0').
The Length property of a string
String objects are immutable

6. Creating, Manipulating, Format, and Comparing Strings

7. Using StringBuilder for Fast String Creation
StringBuilder objects are not immutable.

8. Related Topics about String (MSND)

9. Interning of Strings
A table called the intern pool that contains a single reference to each unique literal string
An instance of a literal string with a particular value only exists once in the system
The Intern method
The IsInterned method

10. Arrays: to store multiple variables of the same type
An array can be Single-Dimensional, Multidimensional or Jagged.
The number of dimensions and the length of each dimension can't be changed
The default values of array elements.
A jagged array is an array of arrays.
Arrays are zero indexed: an array with n elements is indexed from 0 to n-1.
Array elements can be of any type, including an array type.
Array types are reference types derived from the abstract base type Array.
To use foreach iteration on all arrays in C#.

12. Dynamically Increase An Array’s Size
Using The List< T> class or the ArrayList class
Frequently used methods and properties in List< T>
Add and AddRange
Insert
Count (is the counterpart of Length property in Array)
ElementAt
Remove and RemoveRange
Sort

13. Casting and Type Conversions
Implicit conversions
Explicit conversions (casts)
Data loss might occur
Convert from a base type to a derived type
User-defined conversions
Conversions with helper classes, such as the System. Convert class

14. Conversion Operators
Conversions are named for the type to which they convert.
Either the type of the argument or the type of the result of the conversion must be the containing type.
Conversions declared as implicit occur automatically when it is required.
Conversions declared as explicit require a cast to be called.
All conversions must be declared as static.

15. Checked
The checked keyword is used to explicitly enable overflow checking for integral-type arithmetic operations and conversions.
When overflow occurs an overflow exception is raise.
The unchecked keyword is used to suppress overflow-checking

16. Common Type System (CTS): Unified Type Hierarchy

17. Value Types Value types derive from System.ValueType
There are two categories of value types: struct and enum
Boxing and Unboxing

18. Boxing and Unboxing
Boxing is the process of converting a value type to the type object or to any interface type implemented by this value type.
Boxing a value type allocates an object instance on the heap and copies the value into the new object
Unboxing extracts the value type from the object.
Boxing is implicit; unboxing is explicit.

19. Unboxing
Checking the object instance to make sure that it is a boxed value of the given value type.
Copying the value from the instance into the value-type variable.

20. Implicit Types To Implicitly type a local variable by var
The compiler determines and assigns the most appropriate type to the variable

21. Anonymous Types
To encapsulate a set of read-only properties into a single object without a type definition.
Using the new operator together with an object initializer
Anonymous types are class types that derive directly from object.
Array of anonymously typed elements

22. if(x.HasValue) j = x.Value;
Nullable types
Being useful when passing data to and from certain databases
The syntax T? is shorthand for Nullable<T>, whereT is a value type.
Assign a value to a nullable type
Nullable<T>.GetValueOrDefault
Use the HasValue and Value read-only properties
if(x.HasValue) j = x.Value;

23. Using Type dynamic
An object of type dynamic bypasses static type checking
At compile time, an element that is typed as dynamic is assumed to support any operation.
The dynamic language runtime (DLR) is a new API in .NET Framework 4.
the dynamic type in C#
the implementation of dynamic programming languages such as IronPython

25. Improve the experience of interoperating with COM APIs

26. Safely Cast by Using as and is Operators

27. See You Next Class
Learn the whole when you are learning, then you are really learning!
Xun Zi