C# Tutorial - 3. Operators, Types, and Variables Tutorial

本文主要介紹C#的Operators、Types和Variables，以供有興趣的朋友參考。

Variables

C# 是強型別語言，因此每一個變數和物件都必須有宣告的型別。

Types

C#內建的基礎型別有:

* Boolean Type - true and false

* numeric types

- Integrals

The Size and Range of C# Integral Types

Type	Size (in bits)	Range
sbyte	8	-128 to 127
byte	8	0 to 255
short	16	-32768 to 32767
ushort	16	0 to 65535
int	32	-2147483648 to 2147483647
uint	32	0 to 4294967295
long	64	-9223372036854775808 to 9223372036854775807
ulong	64	0 to 18446744073709551615
char	16	0 to 65535

- Floating Point

- Decimal

The Floating Point and Decimal Types with Size, precision, and Range

Type	Size (in bits)	precision	Range
float	32	7 digits	1.5 x 10-45 to 3.4 x 1038
double	64	15-16 digits	5.0 x 10-324 to 1.7 x 10308
decimal	128	28-29 decimal places	1.0 x 10-28 to 7.9 x 1028

*String - is a sequence of text characters.

字串物件是不變的，表示一旦建立就無法變更。修改字串會有新字串物件的建立，所以基於效能的考量，必須使用 StringBuilder  類別執行大量的串連或其他所需的字串管理，以後再做更詳細的介紹

C# Character Escape Sequences

Escape Sequence	Meaning
\'	Single Quote
\"	Double Quote
\\	Backslash
\0	Null, not the same as the C# null value
\a	Bell
\b	Backspace
\f	form Feed
\n	Newline
\r	Carriage Return
\t	Horizontal Tab
\v	Vertical Tab

Operators

在 C# 中，運算子是條件或符號，需要以一或多個運算式 (稱為運算元) 做為輸入並傳回值。

Operators with their precedence and Associativity

Category (by precedence)	Operator(s)	Associativity
Primary	x.y  f(x)  a[x]  x++  x--  new  typeof  default  checked  unchecked delegate	left
Unary	+  -  !  ~  ++x  --x  (T)x	left
Multiplicative	*  /  %	left
Additive	+  -	left
Shift	<<  >>	left
Relational	<  >  <=  >=  is as	left
Equality	==  !=	right
Logical AND	&	left
Logical XOR	^	left
Logical OR	|	left
Conditional AND	&&	left
Conditional OR	||	left
Null Coalescing	??	left
Ternary	?:	right
Assignment	=  *=  /=  %=  +=  -=  <<=  >>=  &=  ^=  |=  =>	right