Beginning Microsoft® Visual C#® 2008_Chapter_3_Variables and Expressions

Basic C# Syntax

1. 一開始程式結構還有註解，跟Java沒啥不一樣，很快過去。
2. C#有個特殊註解///，Chapter 31會解釋。

Basic C# Console Application Structure

1. 主程式一樣是static void Main(string[] args)
2. #region  #endregion 程式碼摺疊起來的時候，可以對該區域做一個註解，這註解會顯示在編輯視窗上面。

Variables

1. < type > < name > ;

Simple Types

1. numbers and Boolean
2. the mechanics of storing numbers as a series of 0s and 1s in the memory of a computer

Type	Alias For	Allowed Values
sbyte	System.SByte	Integer between – 128 and 127
byte	System.Byte	Integer between 0 and 255
short	System.Int16	Integer between – 32768 and 32767
ushort	System.UInt16	Integer between 0 and 65535
int	System.Int32	Integer between – 2147483648 and 2147483647
uint	System.UInt32	Integer between 0 and 4294967295
long	System.Int64	Integer between – 9223372036854775808 and 9223372036854775807
ulong	System.UInt64	Integer between 0 and 18446744073709551615

3. The u characters before some variable names are shorthand for unsigned
4. three floating - point variable types: float , double , and decimal
5. The first two store floating points in the form +/ – m × 2e , where the allowed values for m and e differ for each type.
6. decimal uses the alternative form +/ – m × 10e .

Type	Alias For	Min M	Max M	Min E	Max E	Approx. Min Value	Approx. Max Value
float	System.Single	0	224	-149	104	1.5 * 10 -45	3.4 * 10 38
double	System.Double	0	253	-1075	970	5.0 * 10 -324	1.7 * 10 308
decimal	System.Decimal	0	296	-26	0	1.0 * 10 -28	7.9 * 10 28

7. three other simple types:

Type	Alias For	Allowed Values
char	System.Char	Single Unicode character, stored as an integer between 0 and 65535
bool	System.Boolean	Boolean value, true or false
string	System.String	A sequence of characters

Variable Naming

1. basic rules:
• The first character of a variable name must be either a letter, an underscore character ( _ ), or the at symbol ( @ ).
• Subsequent characters may be letters, underscore characters, or numbers
2. no keywords
3. case sensitive

Naming Conventions

1. Hungarian notation: placing a lowercase prefix on all variable names that identify the type
2. it is far better to name variables appropriately for their purpose
3. two naming conventions are used in the .NET Framework namespaces: PascalCase and camelCase .
4. For your simple variables, stick to camelCase. Use PascalCase for certain more advanced naming, which is the Microsoft recommendation.