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
对于int，double等的tostring：
|
C
|
货币
|
2.5.ToString("C")
|
￥2.50
|
|
D
|
十进制数
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25.ToString("D5")
|
00025
|
|
E
|
科学型
|
25000.ToString("E")
|
2.500000E+005
|
|
F
|
固定点
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25.ToString("F2")
|
25.00
|
|
G
|
常规
|
2.5.ToString("G")
|
2.5
|
|
N
|
数字
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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:
| 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%
