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[收藏]Formatting Dates, Times and Numbers in ASP.NET

2010-12-09T01:54:00Z

Formatting Dates, Times and Numbers in ASP.NET

Introduction

Formatting is the process of converting a variable from its native type into a string representation. Anytime you display a DateTime or numeric variables in an ASP.NET page, you are formatting that variable from its native type into some sort of string representation. How a DateTime or numeric variable is formatted depends on the culture settings and the format string. Because dates and numeric values are formatted differently across cultures, the .NET Framework bases its formatting on the specified culture settings. By default, the formatting routines use the culture settings defined on the web server, but you can indicate that a particular culture be used anytime you format. In addition to the culture settings, formatting is also affected by a format string, which spells out the formatting details to apply.

The .NET Framework contains a bounty of format strings. There are standard format strings, which are typically a single letter that applies detailed formatting logic. For example, the "C" format specifier will format a numeric type as a currency value; the "Y" format specifier displays the month name and four-digit year of the specified DateTime value. There are also custom format strings, which display a apply a very specific formatting rule. These custom format strings can be put together to build more intricate formats. For instance, the format string "dddd, MMMM d" displays the full day of the week name followed by a comma followed by the full name of the month followed by the day of the month. For more involved formatting scenarios, where neither the standard or custom format strings cut the mustard, you can always create your own formatting extension methods.

This article explores the standard format strings for dates, times and numbers and includes a number of custom formatting methods I've created and use in my own projects. There's also a demo application you can download that lets you specify a culture and then shows you the output for the standard format strings for the selected culture. Read on to learn more!

Formatting Basics

There are a couple of different ways to format a DateTime or numeric variable. The first way involves using the ToString method, which has a number of overrides. For DateTime variables:

DateTime.ToString() - converts the value of the DateTime to a string representation using the current culture and the "G" format string. (See the table below to see the output of the "G" format string.)
DateTime.ToString(string) - converts the value of the DateTime to a string representation using the current culture and the specified format string.
DateTime.ToString(IFormatProvider) - converts the value of the DateTime to a string representation using the specified culture settings and the "G" format string.
DateTime.ToString(string, IFormatProvider) - converts the value of the DateTime to a string representation using the specified culture settings and the specified format string.

Numeric variables - integers, doubles, decimals, and so on - have the same ToString method and ToString overloads.

Formatting can also be performed using the String.Format method. The String.Format method accepts as input a format string that contains a number of placeholders, followed by the values to plug into those placeholders. Placeholders take the form {0}, {1}, and so on, and may optional include a format string like so: {0:formatString}. The following code snippet shows using the String.Format method with three placeholders. The values plugged into these placeholders are a string and two decimal values that are both formatted as currencies using the "C" format string within the placeholder syntax.

string customerName = "Tito";
decimal subTotal = 245.13;
decimal taxTotal = 18.94;

// OUTPUT FOR EN-US CULTURE: Tito, your order subtotal is $245.13. Tax is $18.94.
string output = string.Format("{0}, your order subtotal is {1:c}. Tax is {2:c}.", customerName, subTotal, taxTotal);

In the example above, the String.Format method uses the current culture. You can optionally supply the culture settings as the first parameter to the String.Format method.

Standard Date/Time Format Strings

There are 15 standard date and time format strings defined in the .NET Framework. These 15 format strings are detailed on MSDN at Standard Date and Time Format Strings. The table below shows these 15 standard format strings, providing a brief description, code snippet, and sample output using the en-US culture settings. The code snippets reference DateTime.Now, which returns the current date and time. The output column shows the results when this code was executed on my computer at November 8th, 2010 at 3:39 PM.

Format Description	Code Snippet	Output
Short date pattern (d)	DateTime.Now.ToString("d")	11/8/2010
Long date pattern (D)	DateTime.Now.ToString("D")	Monday, November 08, 2010
Full date/time pattern - short time (f)	DateTime.Now.ToString("f")	Monday, November 08, 2010 3:39 PM
Full date/time pattern - long time (F)	DateTime.Now.ToString("F")	Monday, November 08, 2010 3:39:46 PM
General date/time pattern - short time (g)	DateTime.Now.ToString("g")	11/8/2010 3:39 PM
General date/time pattern - long time (G)	DateTime.Now.ToString("G")	11/8/2010 3:39:46 PM
Month/day pattern (M)	DateTime.Now.ToString("M")	November 08
Round-trip date/time pattern (O)	DateTime.Now.ToString("O")	2010-11-08T15:39:46.4804000-08:00
RFC 1123 pattern (R)	DateTime.Now.ToString("R")	Mon, 08 Nov 2010 15:39:46 GMT
Sortable date/time pattern (s)	DateTime.Now.ToString("s")	2010-11-08T15:39:46
Short time pattern (t)	DateTime.Now.ToString("t")	3:39 PM
Long time pattern (T)	DateTime.Now.ToString("T")	3:39:46 PM
Universal sortable date/time pattern (u)	DateTime.Now.ToString("u")	2010-11-08 15:39:46Z
Universal full date/time pattern (U)	DateTime.Now.ToString("U")	Monday, November 08, 2010 11:39:46 PM
Year/month pattern (Y)	DateTime.Now.ToString("Y")	November, 2010

Keep in mind that the output of the standard format strings depend on the culture settings. For example, formatting November 8th, 2010 using the short date pattern displays 11/8/2010 when using the en-US culture; however, the French (France) culture (fr-FR) displays 08/11/2010; German (Germany) shows 08.11.2010; and the Japanese culture outputs 2010/11/08. The download available at the end of this article provides a web page with a drop-down of all available cultures. You can select a culture and see the output for all of the standard date and time format strings.

If you do not explicitly specify a culture when formatting the .NET Framework uses the current culture settings. For an ASP.NET application, these are the culture settings defined on the web server, not the culture settings of the user visiting your site. To learn how to override the web server's culture settings, either for the entire application or on a page-by-page basis, refer to How to: Set the Culture and UI Culture for ASP.NET Web Page Globalization.

Custom Date/Time Format Strings

There are a variety of custom date and time format strings, which allow the page developer to define intricate formatting logic through a number of incremental rules. The custom format strings are detailed on MSDN at Custom Date and Time Format Strings. The table below shows just a few examples of how these custom format strings can be strung together. The code snippets reference DateTime.Now, which returns the current date and time. The output column shows the results when this code was executed on my computer at November 8th, 2010 at 3:39 PM.

Format Description	Code Snippet	Output
Abbreviated month name, day and year	DateTime.Now.ToString("MMM d, yyyy")	Nov 8, 2010
Day of the week name plus month name and day of month	DateTime.Now.ToString("dddd, MMMM d")	Monday, November 8
Month/Day/Year, using exactly two digits for each	DateTime.Now.ToString("MM/dd/yy")	11/08/10

As with the standard format strings, the individual pieces of the custom format strings are culture-specific. The day of the week names and month names, for instance, differ based on the culture.

My Date/Time Formatting Methods

Over my years building ASP.NET applications, I've needed alternate formats for date and time variables that aren't supported by .NET's standard or custom formatting strings. For instance, I have a ToUniversalFormat method that is similar to the "U" format string, but is more compact. In many applications I opt to show DateTime variables as relative times. For example, rather than showing the exact date and time a post was made it is often a better idea to show a relative time, like, "A few minutes ago," or, "Six days ago." As discussed in Advice for Storing and Displaying Dates and Times Across Different Time Zones, displaying relative times removes any issues with time zone differences between the web server and visitors, which is why I prefer this formatting tactic.

These custom formatting methods of mine are implemented as extension methods. Extension methods allow for a developer to seemingly add methods to an existing type (such as the DateTime type). Consequently, my methods - ToRelativeDateString and ToUniversalFormat - look as if they're methods defined on the DateTime structure rather than methods I created. This is the beauty of extension methods. In the demo available for download these extension methods can be found in the App_Code folder.

Some of the code snippets below reference DateTime.Now, which returns the current date and time. The output column shows the results when this code was executed on my computer at November 8th, 2010 at 3:39 PM.

Format Description	Code Snippet	Output
Relative time for date more than a year ago	var birthDate = new DateTime(2008, 9, 1 9, 45, 0); birthDate.ToRelativeDateString()	on September 1, 2008
Relative time for date several months ago	DateTime.Now.AddMonths(-6).ToRelativeDateString()	on May 8
Relative time for date five days ago	DateTime.Now.AddDays(-5).ToRelativeDateString()	five days ago
Relative time for yesterday	DateTime.Now.AddDays(-1).ToRelativeDateString()	yesterday
Relative time for several hours ago	DateTime.Now.AddHours(-3.14159).ToRelativeDateString()	three hours ago
Relative time for more than five minutes ago	DateTime.Now.AddMinutes(-6.25).ToRelativeDateString()	six minutes ago
Relative time for less than five minutes ago	DateTime.Now.AddMinutes(-2.5).ToRelativeDateString()	a few minutes ago
Relative time for within past minute	DateTime.Now.AddSeconds(-15).ToRelativeDateString()	less than a minute ago
Universal format for date in current year	DateTime.Now.ToUniversalFormat()	Monday, Nov 8 at 3:39 PM
Universal format for date in other year	var birthDate = new DateTime(2008, 9, 1 9, 45, 0); birthDate.ToUniversalFormat()	Monday, Sep 1, 2008 at 9:45 AM

Standard Numeric Format Strings

There are nine standard numeric format strings defined in the .NET Framework. These format strings are detailed on MSDN at Standard Numeric Format Strings. The table below shows these nine standard format strings, providing a brief description, code snippet, and sample output using the en-US culture settings. Note that some of these format strings allow an option precision to be specified, which affects how many significant digits or how many digits after the decimal place are displayed. For these I've included an example specifying an explicit precision value, which is why there are more than nine rows in the table below.

Format Description	Code Snippet	Output
Currency with default precision (C)	3.14159.ToString("C")	$3.14
Currency with specified precision (CN)	3.14159.ToString("C4")	$3.1416
Decimal with default precision (D)	32534.ToString("D")	32534
Decimal with specified precision (DN)	32534.ToString("D10")	0000032534
Exponential (E)	123456789.ToString("E")	1.234568E+008
Fixed point with default precision (F)	3.14159.ToString("F")	3.14
Fixed point with specified precision (FN)	3.14159.ToString("F4")	3.1416
General with default precision (G)	3.14159.ToString("G")	3.14159
General with specified precision (GN)	3.14159.ToString("G2")	3.1
Number with default decimal places (N)	3.14159.ToString("N")	3.14
Number with specified decimal places (NN)	3.14159.ToString("N3")	3.142
Percent with default decimal places (P)	0.8752.ToString("P")	87.52 %
Percent with specified decimal places (PN)	0.8752.ToString("P0")	88 %
Round-trip (R)	3.14159.ToString("R")	3.14159
Hexadecimal (X)	183.ToString("X")	B7

As with the date and time format strings, the numeric formatting is culture-sensitive. Different cultures use different grouping separators (commas vs. spaces vs. periods), different currency symbols, and different decimal place characters (periods vs. commas). Be sure to download the demo to view how formatted numbers look differently with alternative culture settings.

Custom Numeric Format Strings

There are a few custom numeric format strings, which allow the page developer to define intricate formatting logic through a number of incremental rules. The custom format strings are detailed on MSDN at Custom Numeric Format Strings. The table below shows just a few examples of how these custom format strings can be strung together. As with the standard format strings, the individual pieces of the custom format strings are culture-specific. For example, the group separator and decimal point displayed depend on the configured culture.

Note the selection separator format string, which allows you to specify different formats for when a number is positive, negative, and zero. The format string #,000.00;(#,000.00);Zero says, "Use the format string #,000.00 when the number is positive, (#,000.00) when it's negative, and Zero when it's zero." The last three rows in the grid below show how the appropriate format string is applied based on the value of the number being formatted.

Format Description	Code Snippet	Output
Zero placeholder (0)	3.14.ToString("00.0000")	03.1400
Zero placeholder (0)	123.45678.ToString("00.0000")	123.4568
Digit (#) and zero (0) placeholders	3.14.ToString("#0.000#")	3.140
Digit (#) and zero (0) placeholders	123.45678.ToString("#0.000#")	123.4568
Group separator placeholder (,)	123456.ToString("#,000.00")	123,456.0
Group separator placeholder (,)	123456789.ToString("#,000.00")	123,456,789.0
Group separator placeholder (,)	123456789876.ToString("#,000.00")	123,456,789,876.0
Section separator (;)	12345.67.ToString("#,000.00;(#,000.00);Zero")	12,345.67
Section separator (;)	(-12345.67).ToString("#,000.00;(#,000.00);Zero")	(12,345.67)
Section separator (;)	0.ToString("#,000.00;(#,000.00);Zero")	Zero

My Numeric Formatting Methods

I have a number of numeric formatting methods I've used in my projects over the years. There's the ToAbbreviatedFormat method, which is useful when displaying larger integer numbers in a confined space when the actual number itself isn't as important as the relative size. For instance, ToAbbreviatedFormat displays a number like 45,431 as 45k. There's also a ToStringAsText method that displays the integer numbers one through ten as English, rather than as a number.

Format Description	Code Snippet	Output
Abbreviated format (less than 1,000)	34.ToAbbreviatedFormat()	34
Abbreviated format (greater than 1,000)	9876.ToAbbreviatedFormat()	9k
Abbreviated format (greater than 1,000)	12345678.ToAbbreviatedFormat()	12,345k
To string as text (capitalized)	3.ToStringAsText(true)	Three
To string as text (not capitalized)	6.ToStringAsText(false)	six
To string as text (greater than 10)	1234.ToStringAsText(false)	1,234

Conclusion

Formatting is a common task in an ASP.NET application and, not surprisingly, the .NET Framework offers a number of techniques for formatting both DateTime and numeric variables. Formatting a date, time, or numeric value involves two parameters - the culture settings and a format string. If omitted, the current culture is used and a default format string is assumed. The format string can be either a standard format string or one built from the various custom format strings. Additionally, you can create your own formatting methods for scenarios that cannot be handled by the existing formatting strings.

Demo Code

From:http://www.4guysfromrolla.com/articles/111010-1.aspx

本文链接

C#条件编译选项:Conditional(代替#if...#endif)

2010-04-21T03:11:00Z

#if (Debug && Trace)
#define DebugAndTrace
#endif

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            Print1();
            Print2();
            Print3();
        }

[Conditional("DEBUG")]
        static void Print1()
        {
            Console.WriteLine("You defined the Debug parameter");
        }

//定义了Debug或者Trace后才会执行
        //或者的关系
        [Conditional("Debug"), Conditional("Trace")]
        static void Print2()
        {
            Console.WriteLine("You defined the Debug or Trace parameter");
        }

        //只有定义了Debug和Trace后才会执行此方法
        [Conditional("DebugAndTrace")]
        static void Print3()
        {
            Console.WriteLine("You defined the Debug and Trace parameter");
        }
    }
}
From MSDN:http://msdn.microsoft.com/zh-cn/library/system.diagnostics.conditionalattribute.aspx
可以使用下面的技术来定义条件编译符号：

编译器命令行选项（例如，/define:DEBUG）,
可以在VS2008的IDE进行设置, Project Property--->Build--->Conditional compilation symbols(如果多个科研使用逗号隔开)
系统默认设置了:DEBUG 和 TRACE

操作系统外壳程序中的环境变量（例如，set DEBUG=1）。

源代码中的杂注（例如，用于定义编译变量的 #define DEBUG，以及用于取消定义它的 #undef DEBUG）。
     必须在file的最前方设置,#define debug或者组合操作
    #if (Debug && Trace)
        #define DebugAndTrace
    #endif

允许符合公共语言规范 (CLS) 的编译器忽略 ConditionalAttribute。C#、J# 和 Visual Basic 编译器支持 ConditionalAttribute；C++ 和 JScript 编译器不支持此属性。

本文链接

不重启电脑进行修改机器名

2010-04-16T07:26:00Z

今天上午遇到一个烦人的问题,电脑已经加入域了,想把计算名修改了,可是死活不行,总提示域中已经有这个名称,可是这个名字的电脑我已经退域了而且还就得使用这个名字。奶奶的搞不定了啊无奈之下求助Google搜到下面的内容。

不过我只用的第一种方法,修改注册表。搞定了啊~~~~

不重启，用bat文件直接修改计算机名和工作组

在系统属性那里修改计算机名或者工作组，总是要进行重新启动，麻烦。

其实计算机名是保存在注册表里面的，我们可以通过直接修改注册表，达到修改的目的。

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\ComputerName\ActiveComputerName

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters

工作组的修改可以通过一个wmic命令来实现目的。

wmic computersystem where Name="%COMPUTERNAME%" call JoinDomainOrWorkgroup Name="%WORKGROUP%"

现在我们把它写成一个批处理，来实现无需重启修改计算机名和工作组：

@echo off

echo AppLife.Net

set /p name=请输您的计算机名：

reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\ComputerName\ActiveComputerName" /v ComputerName /t reg_sz /d %name% /f >nul 2>nul

reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters" /v "NV Hostname" /t reg_sz /d %name% /f >nul 2>nul

reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters" /v Hostname /t reg_sz /d %name% /f >nul 2>nul

echo.

echo 修改计算机名完毕

echo.

echo AppLife.Net

set /p work1=请输入您的工作组名：

wmic computersystem where Name="%COMPUTERNAME%" call JoinDomainOrWorkgroup Name="%work1%"

echo 修改工作组完毕

pause>nul

echo.

把上面的代码保存为一个bat文件，运行就可以了。

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/Teng_s2000/archive/2010/04/16/5493267.aspx

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如何判断当前浏览器是否是IE8?

2009-07-20T09:35:00Z

如何判断当前浏览器是否是IE8?

使用X-UA-Compatible来设置IE8兼容模式

2009-07-20T09:18:00Z

使用X-UA-Compatible来设置IE8兼容模式

给你的网站添加IE8的网页快讯(webslices)

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使用 Windows PowerShell 实现 Web UI 自动化

在asp.net中显示PDF的方法

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C#反转单向链表的两种实现

2009-02-04T09:18:00Z

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VS2008在IE8下开发遇到的问题

2009-02-03T09:55:00Z

VS2008在IE8下开发遇到的问题