public class SingletonDemo
{
private static SingletonDemo theSingleton = null;
private SingletonDemo() { }
public static SingletonDemo Instance()
{
if (theSingleton == null)
{
theSingleton = new SingletonDemo();
}
return theSingleton;
}
static void Main(string[] args)
{
SingletonDemo s1 = SingletonDemo.Instance();
SingletonDemo s2 = SingletonDemo.Instance();
if (s1.Equals(s2))
{
Console.WriteLine("see, only one instance!");
}
}
}
分类目录归档:C#
C#中同步、异步读取进程输出信息
1、异步的:
p.StartInfo.RedirectStandardError = true;
p.ErrorDataReceived += new DataReceivedEventHandler(OutputInfo);
p.Start();
p.BeginErrorReadLine();
private void OutputInfo(object sendProcess, DataReceivedEventArgs output){
if (!String.IsNullOrEmpty(output.Data))
{
//处理方法...
}
}
2、同步的
p.StartInfo.RedirectStandardError = true;
p.Start();
StreamReader sr = ffmpeg.StandardError;
p.WaitForExit();//之后就可以从sr里读了
C#中枚举类型enum的使用
1、关于enum的定义
enum Fabric
{
Cotton = 1,
Silk = 2,
Wool = 4,
Rayon = 8,
Other = 128
}
2、符号名和常数值的互相转换
Fabric fab = Fabric.Cotton;
int fabNum = (int)fab;//转换为常数值。必须使用强制转换。
Fabric fabString = (Fabric)1;//常数值转换成符号名。如果使用ToString(),则是((Fabric)1).ToString(),注意必须有括号。
string fabType = fab.ToString();//显示符号名
string fabVal = fab.ToString ("D");//显示常数值
3、获得所有符号名的方法(具体参见Enum类)
public enum MyFamily
{
YANGZHIPING = 1,
GUANGUIQIN = 2,
YANGHAORAN = 4,
LIWEI = 8,
GUANGUIZHI = 16,
LISIWEN = 32,
LISIHUA = 64,
}
foreach (string s in Enum.GetNames(typeof(MyFamily)))
{
Console.WriteLine(s);
}
4、将枚举作为位标志来处理
根据下面的两个例子,粗略地说,一方面,设置标志[Flags]或者[FlagsAttribute],则表明要将符号名列举出来;另一方面,可以通过强制转换,将数字转换为符号名。说不准确。看下面的例子体会吧。注意:
- 例一:
Fabric fab = Fabric.Cotton | Fabric.Rayon | Fabric.Silk;
Console.WriteLine("MyFabric = {0}", fab);//输出:Fabric.Cotton | Fabric.Rayon | Fabric.Silk;
- 例二:
class FlagsAttributeDemo
{
// Define an Enum without FlagsAttribute.
enum SingleHue : short
{
Black = 0,
Red = 1,
Green = 2,
Blue = 4
};
// Define an Enum with FlagsAttribute.
[FlagsAttribute]
enum MultiHue : short
{
Black = 0,
Red = 1,
Green = 2,
Blue = 4
};
static void Main( )
{
Console.WriteLine(
"This example of the FlagsAttribute attribute n" +
"generates the following output." );
Console.WriteLine(
"nAll possible combinations of values of an n" +
"Enum without FlagsAttribute:n" );
// Display all possible combinations of values.
for( int val = 0; val <= 8; val++ )
Console.WriteLine( "{0,3} – {1}", val, ( (SingleHue)val ).ToString( ) );
Console.WriteLine( "nAll possible combinations of values of an n" + "Enum with FlagsAttribute:n" );
// Display all possible combinations of values.
// Also display an invalid value.
for( int val = 0; val <= 8; val++ )
Console.WriteLine ( "{0,3} – {1}", val, ( (MultiHue)val ).ToString( ) );
}
}
/*
This example of the FlagsAttribute attribute
generates the following output.
All possible combinations of values of an
Enum without FlagsAttribute:
0 – Black
1 – Red
2 – Green
3 – 3
4 – Blue
5 – 5
6 – 6
7 – 7
8 – 8
All possible combinations of values of an
Enum with FlagsAttribute:
0 – Black
1 – Red
2 – Green
3 – Red, Green
4 – Blue
5 – Red, Blue
6 – Green, Blue
7 – Red, Green, Blue
8 – 8
*/
5、枚举作为函数参数。经常和switch结合起来使用。下面举例
public static double GetPrice(Fabric fab)
{
switch (fab)
{
case Fabric.Cotton:
return (3.55);
case Fabric.Silk:
return (5.65);
case Fabric.Wool:
return (4.05);
case Fabric.Rayon:
return (3.20);
case Fabric.Other:
return (2.50);
default:
return (0.0);
}
}
6、上面三点一个完整的例子
//enum的定义
public enum Fabric : short
{
Cotton = 1,
Silk = 2,
Wool = 3,
Rayon = 8,
Other = 128
}
//将枚举作为参数传递
public static double GetPrice(Fabric fab)
{
switch (fab)
{
case Fabric.Cotton: return (3.55);
case Fabric.Silk : return (5.65);
case Fabric.Wool: return (4.05);
case Fabric.Rayon: return (3.20);
case Fabric.Other: return (2.50);
default: return (0.0);
}
}
public static void Main()
{
Fabric fab = Fabric.Cotton;
int fabNum = (int)fab;
string fabType = fab.ToString();
string fabVal = fab.ToString ("D");
double cost = GetPrice(fab);
Console.WriteLine("fabNum = {0}nfabType = {1}nfabVal = {2}n", fabNum, fabType, fabVal);
Console.WriteLine("cost = {0}", cost);
}
7、Enum类的使用
Enum.IsDefinde
、Enum.Parse
两种方法经常一起使用,来确定一个值或符号是否是一个枚举的成员,然后创建一个实例。Enum.GetName
打印出一个成员的值;Enum.GetNames
打印出所有成员的值。其中注意**“`typeof“`**的使用。这一点很重要。
public enum MyFamily
{
YANGZHIPING = 1,
GUANGUIQIN = 2,
YANGHAORAN = 4,
LIWEI = 8,
GUANGUIZHI = 16,
LISIWEN = 32,
LISIHUA = 64,
}
string s = "YANGHAORAN";
if (Enum.IsDefined(typeof(MyFamily), s))
{
MyFamily f = (MyFamily)Enum.Parse(typeof(MyFamily), s);
GetMyFamily(f);
Console.WriteLine("The name is:" + Enum. GetName(typeof(MyFamily), 2));
string[] sa = Enum.GetNames(typeof(MyFamily));
foreach (string ss in sa)
{
Console.WriteLine(ss);
}
}
list contains 类
Subscription sub = new Subscription();
sub.Appname = subName;
if (this.Subscriptions.Contains(sub,new SubcriptionComparer<Subscription>()))
return true;
else
return false;
class SubcriptionComparer<T> : IEqualityComparer<T>
where T : Subscription
{
public int GetHashCode(T obj)
{
return obj.GetHashCode();
}
public bool Equals(T t1, T t2)
{
return t1.Appname == t2.Appname;
}
}
Rhino.Mocks.Exceptions.ExpectationViolationException : Expected #0, Actual #1.
failed: Rhino.Mocks.Exceptions.ExpectationViolationException : IBandwidthDataService.GetDataForCustom(100, 2010/1/11 14:35:31, 2010/2/11 14:35:31, 1.00:00:00); Expected #0, Actual #1.
模拟的方法加上.IgnoreArguments()
C#中class和struct的区别和用法
1,class 是引用类型,structs是值类型
既然class是引用类型,class可以设为null。但是我们不能将struct设为null,因为它是值类型。
struct AStruct
{
int aField;
}
class AClass
{
int aField;
}
class MainClass
{
public static void Main()
{
AClass b = null; // No error.
AStruct s = null; // Error [ Cannot convert null to 'AStruct'
because it is a value type ].
}
}
2,当你实例一个class,它将创建在堆上。而你实例一个struct,它将创建在栈上
3,你使用的是一个对class实例的引用。而你使用的不是对一个struct的引用。(而是直接使用它们)
4,当我们将class作为参数传给一个方法,我们传递的是一个引用。struct传递的是值而非引用。
5,structs, 不可以有初始化器,class可以有初始化器。
class MyClass
{
int myVar =10; // no syntax error.
public void MyFun( )
{
// statements
}
}
struct MyStruct
{
int myVar = 10; // syntax error.
public void MyFun( )
{
// statements
}
}
6,Classes 可以有明显的无参数构造器,但是Struct不可以
class MyClass { int myVar = 10; public MyClass( ) // no syntax error. { // statements } } struct MyStruct { int myVar; public MyStruct( ) // syntax error. { // statements } }
7, 类使用前必须new关键字实例化,Struct不需要
MyClass aClassObj; // MyClass aClassObj=new MyClass(); is the correct format.aClassObj.
myVar=100;//NullReferenceException(because aClassObj does not contain a reference to an object of type myClass).
MyStruct aStructObj;
aStructObj.myVar=100; // no exception.
8, class支持继承和多态,Struct不支持. 注意:但是Struct 可以鹤类一样实现接口
9, 既然Struct不支持继承,其成员不能以protected 或Protected Internal 修饰
10, Class的构造器不需要初始化全部字段,Struct的构造器必须初始化所有字段
class MyClass //No error( No matter whether the Field ’ MyClass.myString ’ is initialized or not ).
{
int myInt;
string myString;
public MyClass( int aInt )
{
myInt = aInt;
}
}
struct MyStruct // Error ( Field ’ MyStruct.myString ’ must be fully assigned before it leaves the constructor ).
{
int myInt;
string myString;
public MyStruct( int aInt )
{
myInt = aInt;
}
}
11, Class可以定义析构器但是Struct不可以
12, Class比较适合大的和复杂的数据,Struct适用于作为经常使用的一些数据组合成的新类型。
适用场合:Struct有性能优势,Class有面向对象的扩展优势。
用于底层数据存储的类型设计为Struct类型,将用于定义应用程序行为的类型设计为Class。如果对类型将来的应用情况不能确定,应该使用Class。
c#中如何将string 转 byte
System.Text.Encoding.Default.GetBytes(string);
反之亦然
System.Text.Encoding.Default.GetString(byte);
C# 合并两个 list
using System;
using System.Collections.Generic;
class Program
{
static void Main()
{
List a = new List();
a.Add(1);
a.Add(2);
a.Add(5);
a.Add(6);
// Contains:
// 1
// 2
// 5
// 6
int[] b = new int[3];
b[0] = 7;
b[1] = 6;
b[2] = 7;
a.AddRange(b);
// Contains:
// 1
// 2
// 5
// 6
// 7 [added]
// 6 [added]
// 7 [added]
foreach (int i in a)
{
Console.WriteLine(i);
}
}
}
=== Output of the program ===
1
2
5
6
7
6
7
String.Format格式说明
C#格式化数值结果表
字符 | 说明 | 示例 | 输出 |
---|---|---|---|
C | 货币 | string.Format("{0:C3}", 2) |
$2.000 |
D | 十进制 | string.Format("{0:D3}", 2) |
002 |
E | 科学计数法 | 1.20E+001 |
1.20E+001 |
G | 常规 | string.Format("{0:G}", 2) |
2 |
N | 用分号隔开的数字 | string.Format("{0:N}", 250000) |
250,000.00 |
X | 十六进制 | string.Format("{0:X000}", 12) |
C |
string.Format("{0:000.000}", 12.2) |
012.200 |
Strings
There really isn’t any formatting within a strong, beyond it’s alignment. Alignment works for any argument being printed in a String.Format call.
Sample | Generates |
---|---|
String.Format("->{1,10}<-", "Hello"); |
-> Hello<- |
String.Format("->{1,-10}<-", "Hello"); |
->Hello <- |
Numbers
Basic number formatting specifiers:
Specifier | Type | Format | Output (Passed Double 1.42) | Output (Passed Int -12400) |
c | Currency | {0:c} | $1.42 | -$12,400 |
d | Decimal (Whole number) | {0:d} | System.FormatException | -12400 |
e | Scientific | {0:e} | 1.420000e+000 | -1.240000e+004 |
f | Fixed point | {0:f} | 1.42 | -12400.00 |
g | General | {0:g} | 1.42 | -12400 |
n | Number with commas for thousands | {0:n} | 1.42 | -12,400 |
r | Round trippable | {0:r} | 1.42 | System.FormatException |
x | Hexadecimal | {0:x4} | System.FormatException | cf90 |
Custom number formatting:
Specifier | Type | Example | Output (Passed Double 1500.42) | Note |
---|---|---|---|---|
0 | Zero placeholder | {0:00.0000} | 1500.4200 | Pads with zeroes. |
# | Digit placeholder | {0:(#).##} | (1500).42 | |
. | Decimal point | {0:0.0} | 1500.4 | |
, | Thousand separator | {0:0,0} | 1,500 | Must be between two zeroes. |
,. | Number scaling | {0:0,.} | 2 | Comma adjacent to Period scales by 1000. |
% | Percent | {0:0%} | 150042% | Multiplies by 100, adds % sign. |
e | Exponent placeholder | {0:00e+0} | 15e+2 | Many exponent formats available. |
; | Group separator | see below |
The group separator is especially useful for formatting currency values which require that negative values be enclosed in parentheses. This currency formatting example at the bottom of this document makes it obvious:
Dates
Note that date formatting is especially dependant on the system’s regional settings; the example strings here are from my local locale.
Specifier | Type | Example (Passed System.DateTime.Now) |
d | Short date | 10/12/2002 |
D | Long date | December 10, 2002 |
t | Short time | 10:11 PM |
T | Long time | 10:11:29 PM |
f | Full date & time | December 10, 2002 10:11 PM |
F | Full date & time (long) | December 10, 2002 10:11:29 PM |
g | Default date & time | 10/12/2002 10:11 PM |
G | Default date & time (long) | 10/12/2002 10:11:29 PM |
M | Month day pattern | December 10 |
r | RFC1123 date string | Tue, 10 Dec 2002 22:11:29 GMT |
s | Sortable date string | 2002-12-10T22:11:29 |
u | Universal sortable, local time | 2002-12-10 22:13:50Z |
U | Universal sortable, GMT | December 11, 2002 3:13:50 AM |
Y | Year month pattern | December, 2002 |
The ‘U’ specifier seems broken; that string certainly isn’t sortable.
Custom date formatting:
Specifier | Type | Example | Example Output |
dd | Day | {0:dd} | 10 |
ddd | Day name | {0:ddd} | Tue |
dddd | Full day name | {0:dddd} | Tuesday |
f, ff, … | Second fractions | {0:fff} | 932 |
gg, … | Era | {0:gg} | A.D. |
hh | 2 digit hour | {0:hh} | 10 |
HH | 2 digit hour, 24hr format | {0:HH} | 22 |
mm | Minute 00-59 | {0:mm} | 38 |
MM | Month 01-12 | {0:MM} | 12 |
MMM | Month abbreviation | {0:MMM} | Dec |
MMMM | Full month name | {0:MMMM} | December |
ss | Seconds 00-59 | {0:ss} | 46 |
tt | AM or PM | {0:tt} | PM |
yy | Year, 2 digits | {0:yy} | 02 |
yyyy | Year | {0:yyyy} | 2002 |
zz | Timezone offset, 2 digits | {0:zz} | -05 |
zzz | Full timezone offset | {0:zzz} | -05:00 |
: | Separator | {0:hh:mm:ss} | 10:43:20 |
/ | Separator | {0:dd/MM/yyyy} | 10/12/2002 |
Enumerations
Specifier | Type |
g | Default (Flag names if available, otherwise decimal) |
f | Flags always |
d | Integer always |
x | Eight digit hex. |
Some Useful Examples
String.Format("{0:$#,##0.00;($#,##0.00);Zero}", value);
This will output "$1,240.00" if passed 1243.50. It will output the same format but in parentheses if the number is negative, and will output the string "Zero" if the number is zero.
String.Format("{0:(###) ###-####}", 18005551212);
This will output "(800) 555-1212".
变量.ToString()
字符型转换 转为字符串
12345.ToString("n"); //生成 12,345.00
12345.ToString("C"); //生成 ¥12,345.00
12345.ToString("e"); //生成 1.234500e+004
12345.ToString("f4"); //生成 12345.0000
12345.ToString("x"); //生成 3039 (16进制)
12345.ToString("p"); //生成 1,234,500.00%
C# List 排序
写一个sorter
public class CourseSorter:IComparer
{
#region IComparer Members
public int Compare(CourseDto x, CourseDto y)
{
return x.Title.CompareTo(y.Title);
}
#endregion
}
用的时候list.sort(new Sorter());
即可