C# 格式化输出

一、字符串的格式化输出

1.1 格式化输出表

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

string.Format(“{0:e}”,1.2)

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

 

1.2 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 <-

1.3 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:

1.4 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.

二、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#:String.Format数字格式化输出

int a = 12345678;
//格式为sring输出
// Label1.Text = string.Format("asdfadsf{0}adsfasdf",a);
// Label2.Text = "asdfadsf"+a.ToString()+"adsfasdf";
// Label1.Text = string.Format("asdfadsf{0:C}adsfasdf",a);//asdfadsf￥1,234.00adsfasdf
// Label2.Text = "asdfadsf"+a.ToString("C")+"adsfasdf";//asdfadsf￥1,234.00adsfasdf

 

double b = 1234.12543;
a = 12345678;
//格式为特殊的string样式输出
// Label1.Text = string.Format("asdfadsf{0:C}adsfasdf",b);//asdfadsf￥1,234.13adsfasdf
// Label2.Text = "asdfadsf"+b.ToString("C")+"adsfasdf";//asdfadsf￥1,234.13adsfasdf
// Label1.Text = string.Format("{0:C3}",b);//￥1,234.125
// Label2.Text = b.ToString("C3");//￥1,234.125
// Label1.Text = string.Format("{0:d}",a);//十进制--12345678
// Label2.Text = b.ToString("d");//十进制--相同的类型，转换报错
// Label1.Text = string.Format("{0:e}",a);//指数--1.234568e+007
// Label2.Text = b.ToString("e");//指数--1.234125e+003

// Label1.Text = string.Format("{0:f}",a);//定点数--12345678.00
// Label2.Text = b.ToString("f");//定点数--1234.13
// Label1.Text = string.Format("{0:n}",a);//数值--12,345,678.00
// Label2.Text = b.ToString("n");//数值--1,234.13
// Label1.Text = string.Format("{0:x}",a);//十六进制--bc614e
// Label2.Text = b.ToString("x");//16--带有小数不能转换，出错
// Label1.Text = string.Format("{0:g}",a);//通用为最紧凑--12345678
// Label2.Text = b.ToString("g");//通用为最紧凑--1234.12543
// Label1.Text = string.Format("{0:r}",a);//转来转去不损失精度--整数不允许用，报错
// Label2.Text = b.ToString("r");//转来转去不损失精度--1234.12543

b = 4321.12543;
a = 1234;
//自定义模式输出：
// 0 描述：占位符，如果可能，填充位
// Label1.Text = string.Format("{0:000000}",a);// 001234
// Label2.Text = string.Format("{0:000000}",b);// 004321
// # 描述：占位符，如果可能，填充位
// Label1.Text = string.Format("{0:#######}",a);// 1234
// Label2.Text = string.Format("{0:#######}",b);// 4321
// Label1.Text = string.Format("{0:#0####}",a);// 01234
// Label2.Text = string.Format("{0:0#0000}",b);// 004321

// . 描述：小数点
// Label1.Text = string.Format("{0:000.000}",a);//1234.000
// Label2.Text = string.Format("{0:000.000}",b);//4321.125
b = 87654321.12543;
a = 12345678;
// , 描述：数字分组，也用于增倍器
// Label1.Text = string.Format("{0:0,00}",a);// 12,345,678
// Label2.Text = string.Format("{0:0,00}",b);// 87,654,32
// Label1.Text = string.Format("{0:0,}",a);// 12346
// Label2.Text = string.Format("{0:0,}",b);// 87654
// Label1.Text = string.Format("{0:0,,}",a);// 12
// Label2.Text = string.Format("{0:0,,}",b);// 88
// Label1.Text = string.Format("{0:0,,,}",a);// 0
// Label2.Text = string.Format("{0:0,,,}",b);// 0
// % 描述：格式为百分数
// Label1.Text = string.Format("{0:0%}",a);// 1234567800%
// Label2.Text = string.Format("{0:#%}",b);// 8765432113%
// Label1.Text = string.Format("{0:0.00%}",a);// 1234567800.00%
// Label2.Text = string.Format("{0:#.00%}",b);// 8765432112.54%
// 'abc' 描述：显示单引号内的文本
// Label1.Text = string.Format("{0:'文本'0}",a);// 文本12345678
// Label2.Text = string.Format("{0:文本 0}",b);// 文本87654321
// / 描述： 后跟1要打印字的字符，也用于转移符/n等
// Label1.Text = string.Format("/"你好！ /"");// "你好！"
// Label2.Text = string.Format("//c//books//new//we.asp");///c/books/new/we.asp
// @描述：后跟要打印字的字符,
// Label1.Text = string.Format(@"""你好！"""); // "你好！"要打印"则需要输入两对才可以
// Label2.Text = string.Format(@"/c/books/new/we.asp");///c/books/new/we.asp

 

百分数格式应该用“p”这个参数。

格式      原始数据    结果 
"{0:P}" 0.40 40%
数字 {0:N2} 12.36 
数字 {0:N0} 13 
货币 {0:c2} $12.36 
货币 {0:c4} $12.3656 
货币 "￥{0:N2}" ￥12.36 
科学计数法 {0:E3} 1.23E+001 
百分数 {0:P} 12.25% P and p present the same. 
日 期 {0:D} 2006年11月25日 
日期 {0:d} 2006-11-25 
日期 {0:f} 2006年11月25日 10:30 
日期 {0:F} 2006年11月25日 10:30:00 
日期 {0:s} 2006-11-26 10:30:00 
时间 {0:T} 10:30:00

DateTime dt = DateTime.Now;
Label1.Text = dt.ToString();//2005-11-5 13:21:25
Label2.Text = dt.ToFileTime().ToString();//127756416859912816
Label3.Text = dt.ToFileTimeUtc().ToString();//127756704859912816
Label4.Text = dt.ToLocalTime().ToString();//2005-11-5 21:21:25
Label5.Text = dt.ToLongDateString().ToString();//2005年11月5日
Label6.Text = dt.ToLongTimeString().ToString();//13:21:25
Label7.Text = dt.ToOADate().ToString();//38661.5565508218
Label8.Text = dt.ToShortDateString().ToString();//2005-11-5
Label9.Text = dt.ToShortTimeString().ToString();//13:21
Label10.Text = dt.ToUniversalTime().ToString();//2005-11-5 5:21:25

Label1.Text = dt.Year.ToString();//2005
Label2.Text = dt.Date.ToString();//2005-11-5 0:00:00
Label3.Text = dt.DayOfWeek.ToString();//Saturday
Label4.Text = dt.DayOfYear.ToString();//309
Label5.Text = dt.Hour.ToString();//13
Label6.Text = dt.Millisecond.ToString();//441
Label7.Text = dt.Minute.ToString();//30
Label8.Text = dt.Month.ToString();//11
Label9.Text = dt.Second.ToString();//28
Label10.Text = dt.Ticks.ToString();//632667942284412864
Label11.Text = dt.TimeOfDay.ToString();//13:30:28.4412864

Label1.Text = dt.ToString();//2005-11-5 13:47:04
Label2.Text = dt.AddYears(1).ToString();//2006-11-5 13:47:04
Label3.Text = dt.AddDays(1.1).ToString();//2005-11-6 16:11:04
Label4.Text = dt.AddHours(1.1).ToString();//2005-11-5 14:53:04
Label5.Text = dt.AddMilliseconds(1.1).ToString();//2005-11-5 13:47:04
Label6.Text = dt.AddMonths(1).ToString();//2005-12-5 13:47:04
Label7.Text = dt.AddSeconds(1.1).ToString();//2005-11-5 13:47:05