c#中的常用ToString()方法总结

很多类都重写了ToString方法， 导致很多类的tostring到底执行了什么，有哪些参数，都不清楚。。。。很郁闷！对于int，double等的tostring：

C

 

 

货币

 

 

2.5.ToString("C")

 

 

￥2.50

 

 

D

 

 

十进制数

 

 

25.ToString("D5")

 

 

00025

 

 

E

 

 

科学型

 

 

25000.ToString("E")

 

 

2.500000E+005

 

 

F

 

 

固定点

 

 

25.ToString("F2")

 

 

25.00

 

 

G

 

 

常规

 

 

2.5.ToString("G")

 

 

2.5

 

 

N

 

 

数字

 

 

2500000.ToString("N")

 

 

2,500,000.00

 

 

X

 

 

十六进制

 

 

255.ToString("X")

 

 

FF

 

格式符

应 用

含 义

示 例

C

数字类型

专用场合的货币值

$4834.50 (USA)

£4834.50 (UK)

D

只用于整数类型

一般的整数

4834

E

数字类型

科学计数法

4.834E+003

F

数字类型

小数点后的位数固定

4384.50

G

数字类型

一般的数字

4384.5

N

数字类型

通常是专用场合的数字 格式

4,384.50 (UK/USA)

4 384,50 (欧洲大陆)

P

数字类型

百分比计数法

432,000.00%

X

只用于整数类型

16进制格式

1120 (如果要显示0x1120，需要写上0x)

 

Custom number formatting:

 

SpecifierTypeExample Output (Passed Double 1500.42)Note0Zero placeholder{0:00.0000}1500.4200Pads with zeroes.#Digit placeholder{0:(#).##}(1500).42 .Decimal point{0:0.0}1500.4 ,Thousand separator{0:0,0}1,500Must be between two zeroes.,.Number scaling{0:0,.} 2Comma adjacent to Period scales by 1000.%Percent{0:0%}150042%Multiplies by 100, adds % sign.eExponent placeholder{0:00e+0}15e+2Many exponent formats available.;Group separatorsee 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.

 

SpecifierTypeExample (Passed System.DateTime.Now)dShort date10/12/2002DLong dateDecember 10, 2002tShort time10:11 PMTLong time10:11:29 PMfFull date & time December 10, 2002 10:11 PMFFull date & time (long)December 10, 2002 10:11:29 PMgDefault date & time10/12/2002 10:11 PMGDefault date & time (long)10/12/2002 10:11:29 PMMMonth day patternDecember 10rRFC1123 date stringTue, 10 Dec 2002 22:11:29 GMTsSortable date string2002-12-10T22:11:29uUniversal sortable, local time2002-12-10 22:13:50ZUUniversal sortable, GMTDecember 11, 2002 3:13:50 AMYYear month patternDecember, 2002

The 'U' specifier seems broken; that string certainly isn't sortable.

Custom date formatting:

 

SpecifierTypeExample Example OutputddDay{0:dd}10dddDay name{0:ddd}TueddddFull day name{0:dddd}Tuesdayf, ff, ...Second fractions{0:fff}932gg, ...Era{0:gg}A.D.hh2 digit hour{0:hh}10HH2 digit hour, 24hr format{0:HH}22mmMinute 00-59{0:mm}38MMMonth 01-12{0:MM}12MMMMonth abbreviation{0:MMM}DecMMMMFull month name{0:MMMM}DecemberssSeconds 00-59{0:ss}46ttAM or PM{0:tt}PMyyYear, 2 digits{0:yy}02yyyyYear{0:yyyy}2002zzTimezone offset, 2 digits{0:zz}-05zzzFull timezone offset{0:zzz}-05:00:Separator{0:hh:mm:ss}10:43:20/Separator{0:dd/MM/yyyy}10/12/2002

Enumerations

 

SpecifierTypegDefault (Flag names if available, otherwise decimal)fFlags alwaysdInteger alwaysxEight 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%