查看: 2503|回复: 18

折磨（一）第二的又写到一半忙~~~~~

13 主题	0 好友	2113 积分

白金长老

Rank: 10

发消息

电梯直达

1^#

发表于 2008-12-6 06:23 PM |只看该作者 |倒序浏览

你们要从基础学咯

ok 我这边给你们的是 .net 的写法

基础是几个

c# 是 case sensitivity 的 S != s
vb.net 是没有分的 S = s

注解或 marking

c#

一行的

// this is c#

多行的

/*  this
   is
   C#
*/

vb.net

' this is vb.net
REM this is vb.net

==============================
c# 是以 ; 来区分是不是下一行了
vb 直接 enter

看语法

c#
==============================
string A;
string B = A ;

// 一行的写法
mystring = mystring1 + mystring2 + mystring3;
// 两行的写法
mystring = mystring1 + mystring2 +
                  mystring3;
//三行的写法
mystring = mystring1 +
                  mystring2 +
                  mystring3;
==============================
c# 只要没 ; 就是当成同一行。

vb.net
==============================
dim A as string
dim B as string = A

' 一行的写法
mystring = mystring1 + mystring2 + mystring3
' 两行的写法
mystring = mystring1 + mystring2 + _
                  mystring3
' 三行的写法
mystring = mystring1 + _
                  mystring2 + _
                  mystring3
==============================
vb.net 的只要enter  就是下一行咯只能用 _ 来接下一行是同行

block structure
c# 的是
{ }
==============================

if (a == b)
{
   'abc
}

public bool goodday()
{
   'abc
}

==============================
vb.net
end if end case  end sub end function
==============================

if a = b then
   'abc
End if

public function goodday() as boolean
   'abc
end function

资料类型  data type

Size (bytes)	Visual Basic.net	C#.net	Common Runtime Language	Value Range
01	Byte	byte	System.Byte	0 to 255
01	(Not Implemented)	sbyte	System.Sbyte	-128 to 127
02	Boolean	bool	System.Boolean	True or False only
02	Char	char	System.Char	0 to 65535
02	Short	short	System.Int16	-32,768 to 32,767.
02	(Not Implemented)	ushort	System.UInt16	0 to 65535
04	Integer	int	System.Int32	-2,147,483,648 to 2,147,483,647
04	(Not Implemented)	uint	System.Uint32	0 to 4294967295
04	Single	float	System.Single	-3.4028235E+38 to -1.401298E-45 for negative values; 1.401298E-45 to 3.4028235E+38 for positive values.
04	Object	object	System.Object	Any type can be stored in a variable of type Object.
08	Date	DateTime	System.DateTime	0:00:00 on January 1, 0001 through 11:59:59 PM on December 31, 9999.
08	Long	long	System.Int64	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
08	(Not Implemented)	ulong	System.UInt64	0 to 18446744073709551615
08	Double	double	System.Double	-1.79769313486231570E+308 to -4.94065645841246544E-324 for negative values; 4.94065645841246544E-324 through 1.79769313486231570E+308 for positive values.
16	Decimal	decimal	System.Decimal	0 to +/-79,228,162,514,264,337,593,543,950,335 with no decimal point;0 through +/-7.9228162514264337593543950335 with 28 places to the right of the decimal; smallest nonzero number is +/-0.0000000000000000000000000001 (+/-1E-28).
Varies	structure	struct	System.ValueType	Each member of the structure has a range determined by its data type and independent of the ranges of the other members.
Varies	String	string	System.String	0 to approximately 2 billion Unicode characters

[ 本帖最后由 goodday 于 2008-12-7 11:35 AM 编辑 ]

折磨

收藏0

使用道具举报

goodday

13 主题	0 好友	2113 积分

白金长老

Rank: 10

发消息

2^#

发表于 2008-12-6 06:25 PM |只看该作者

data type 是很基础又很重要的

如果你不明白很难会写个有效率的系统

好像 boolean
你的东西如果只有
对错  是或不是可以不可以

那你用 boolean 咯

好像 integer
他的是由

-2,147,483,648
到
2,147,483,647

你要用的如果不到 20亿那你大可用它咯

但如果你用到 20亿以上
你就得用 long

他是由

-9,223,372,036,854,775,808
到
9,223,372,036,854,775,807.

我肯定你够用啦

否则
overflow exception

你要算什么那么大哦
bill gate 都没那个数字的身家

如果你一直用 long 你就浪费很多的 ram 啦
你的program 越用越慢因为一直要调用资源和回流资源
释放和回流都很慢大嘛

如果你的server 或pc 有 128GB Ram 我没话好说
不用动用那么多的page file 或 swap patition

好啦那么多的废话

回主题

DateTime
这个的 DataType 很复杂
=========================================
vb.net
=========================================

dim ATime as DateTime = new DateTime(2008,01,01,00,00,00)
dim BTime as DateTime = DateTime.Now()
dim CTime as String = DateTime.Now.Year()
dim DTime as DateTime = DateTime.Now.AddDays(100)

=========================================
c#
=========================================

DateTime  ATime = new DateTime(2008,01,01,00,00,00);
DateTime  BTime = DateTime.Now();
String       CTime = DateTime.Now.Year();
DateTime  DTime = DateTime.Now.AddDays(100);

=========================================
以上的答案
=========================================
ATime  = 01/01/2008 12:00:00 am
BTime  = 现在的时间
CTime  = 2008
DTime  = 现在的日期再加 100 天

有用的属性

=========================================
C#
=========================================
DateTime NowTime;

=========================================
VB.net
=========================================
Dim NowTime as DateTime

NowTime.Now    =  现在的时间 --〉 01/01/2008 3:15:00pm
NowTime.Today =  现在的日期 --> 01/01/2008 12:00:00 am

NowTime.Year             = 2008
NowTime.Date             =
NowTime.Day             = 13
NowTime.Hour             =12
NowTime.Minute          =30
NowTime.Second       =30
NowTime.Millisecond  =

Table 1.1 - Standard Format Characters

Format Character	Format Pattern
d	MM/dd/yyyy
D	dddd, MMMM dd, yyyy
f	dddd, MMMM dd, yyyy HH:mm
F	dddd, MMMM dd, yyyy HH:mm:ss
g	MM/dd/yyyy HH:mm
G	MM/dd/yyyy HH:mm:ss
m, M	MMMM dd
r, R	ddd, dd MMM yyyy HH':'mm':'ss 'GMT'
s	yyyy-MM-dd HH:mm:ss
t	HH:mm
T	HH:mm:ss
u	yyyy-MM-dd HH:mm:ss
U	dddd, MMMM dd, yyyy HH:mm:ss
y, Y	MMMM, yyyy

Table 1.2 - List of patterns you can use to create custom formatting

Format Pattern	Description
d	The day of the month. Single-digit days will not have a leading zero.
dd	The day of the month. Single-digit days will have a leading zero.
ddd	The abbreviated name of the day of the week
dddd	The full name of the day of the week
M	The numeric month. Single-digit months will not have a leading zero.
MM	The numeric month. Single-digit months will have a leading zero.
MMM	The abbreviated name of the month
MMMM	The full name of the month
y	The year without the century. If the year without the century is less than 10, the year is displayed with no leading zero.
yy	The year without the century. If the year without the century is less than 10, the year is displayed with a leading zero.
yyyy	The year including the century in four digits.
gg	The period or era. This pattern is ignored if the date to be formatted does not have an associated period or era string.
h	The hour in a 12-hour clock. Single-digit hours will not have a leading zero.
hh, hh*	The hour in a 12-hour clock. Single-digit hours will have a leading zero.
H	The hour in a 24-hour clock. Single-digit hours will not have a leading zero.
HH, HH*	The hour in a 24-hour clock. Single-digit hours will have a leading zero.a
m	The minute. Single-digit minutes will not have a leading zero.
mm, mm*	The minute. Single-digit minutes will have a leading zero.
s	The second. Single-digit seconds will not have a leading zero.
ss, ss*	The second. Single-digit seconds will have a leading zero.
t	The first character in the AM/PM designator
tt, tt*	The AM/PM designator
z	The timezone offset (hour only). Single-digit hours will not have a leading zero.
zz	The timezone offset (hour only). Single-digit hours will have a leading zero.
zzz, zzz*	The full timezone offset (hour and minutes). Single-digit hours and minutes will have leading zeros.
:	The default time separator
/	The default date separator
% c	Where c is a standard format character. Displays the standard format pattern associated with the format character.
\ c	Where c is any character. Displays the character literally.

http://www.dotnetjunkies.ddj.com/Tutorial/9D1C5FBF-FE27-42EA-B8C3-058FF295D822.dcik

http://blog.darkthread.net/blogs/darkthreadtw/archive/2007/04/30/tips-net-datetime-formating.aspx

[ 本帖最后由 goodday 于 2008-12-7 11:33 AM 编辑 ]

使用道具举报

goodhermit95

62 主题	5 好友	3715 积分

本站名嘴

Rank: 11

发消息

3^#

发表于 2008-12-6 07:18 PM |只看该作者

给那些喜欢喜欢就说要学的人看了直接晕倒
原来C# 不用 _ 的
还有多余的设写法
Dim a As String
Dim B As String
a = B
多余的啦，凑行数专用

C#的等于是 == 啊？
那个什么byte的，我都没有用，只要是Byte，ushort等等都用String搞定

打太多string玩GAME打Strong都会打成String

很好的折磨（给新手）

尤其是买菜的

使用道具举报

Super-Tomato

7 主题	1 好友	5108 积分

一流名嘴

Rank: 12

发消息

4^#

发表于 2008-12-6 11:00 PM |只看该作者

原帖由 goodhermit95 于 2008-12-6 07:18 PM 发表
给那些喜欢喜欢就说要学的人看了直接晕倒
原来C# 不用 _ 的
还有多余的设写法
Dim a As String
Dim B As String
a = B
多余的啦，凑行数专用

C#的等于是 == 啊？
那个什么byte的，我都没有用， ...

data type 是一個 programmer 必須了解的基礎, 適當的使用可以減少記憶體上的佔用
ushort 是數字類型無法以 String 來代替

新手不要單單只是背起這些 data type, 必須了解為甚麼 short 和 ushort 是 4 bytes, 而為何起範圍是 65535 的長度, 還有怎麼計算出來等
這些就等 goodday 慢慢解釋給你們聽了