C#中常用的ToString()方法總結

zhoujunfeng19發表於2015-12-18
很多類都重寫了ToString方法, 導致很多類的tostring到底執行了什麼,有哪些引數,都不清楚。。。。很鬱悶!
對於int,double等的tostring:

C

 

 

貨幣

 

 

2.5.ToString("C")

 

 

¥2.50

 

 

D

 

 

十進位制數

 

 

25.ToString("D5")

 

 

00025

 

 

E

 

 

科學型

 

 

25000.ToString("E")

 

 

2.500000E+005

 

 

F

 

 

固定點

 

 

25.ToString("F2")

 

 

25.00

 

 

G

 

 

常規

 

 

2.5.ToString("G")

 

 

2.5

 

 

N

 

 

數字

 

 

2500000.ToString("N")

 

 

2,500,000.00

 

 

X

 

 

十六進位制

 

 

255.ToString("X")

 

 

FF


格式符

 

 

 

C

數字型別

專用場合的貨幣值

$4834.50 (USA)

£4834.50 (UK)

D

只用於整數型別

一般的整數

4834

E

數字型別

科學計數法

4.834E+003

F

數字型別

小數點後的位數固定

4384.50

G

數字型別

一般的數字

4384.5

N

數字型別

通常是專用場合的數字 格式

4,384.50 (UK/USA)

4 384,50 (歐洲大陸)

P

數字型別

百分比計數法

432,000.00%

X

只用於整數型別

16進位制格式

1120 (如果要顯示0x1120,需要寫上0x)


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".

 

變數.ToString()


字元型轉換 轉為字串 
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進位制) 
12345.ToString("p"); //生成 1,234,500.00%

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