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 |
eg.数字的格式指定
可以通过往刚才所说的修饰项目中添加几个参数来实现控制数字格式的目的。下表列出了几个常见的例子。
| 操作格式 | 代码 |
输出 |
| 固定宽度右对齐 | String.Format("{0, 4}", num) |
“ |
| 固定宽度左对齐 | String.Format("{0, -4}", num) |
“1 ” |
| 用0填充 | String.Format("{0:D4}", num)或者 String.Format("{0:0000}", num) |
“0001” |
| 固定宽度并用0填充 | String.Format("{0, 8:D4}", num) |
“ 0001” |
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 |
Output |
|
c |
Currency |
{0:c} |
＄1.42 |
-＄12,400 |
|
d |
Decimal (Whole number) |
{0:d} |
System. |
-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. |
|
x |
Hexadecimal |
{0:x4} |
System. |
cf90 |
Custom number formatting （ Passed Double 1500.42 ) :
|
Specifier |
Type |
Example |
Output |
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