C#中String.Format的使用

String.Format的使用方法如下:
string errorString = String.Format(”Error {0} occurred.”, nError);
其中在花括號中的內容格式如下: {index[,alignment][:formatString]}.
參數說明:
index表示的參數的序列值
alignment表示對齊方式,省略或為正數,則向右靠齊.如果為負,則向左靠齊.不足的部分用空格填充.
formatString表示格式化方式

1.Strings字符串格式化
示例                                                               輸出
String.Format(”->{1,10}<-”, “Hello”);    -> Hello<-
String.Format(”->{1,-10}<-”, “Hello”);   ->Hello <-

2.Numbers數值格式化
--1.基本的格式化字符

 

字符	類型	格式	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

示例:

string.Format("{0:C3}", 2) //輸出 ＄2.000
string.Format("{0:D3}", 2) //輸出 002
string.Format("{0:G}", 2) //輸出 2
string.Format("{0:N}", 250000) //輸出 250,000.00
string.Format("{0:X000}", 12) //輸出 C

--2.自定義數值格式

字符	類型	示例	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	參見示例

 示例:

String.Format("{0:0000}",157)                                      //輸出 0157
String.Format("{0:0000.0000}",157.42)                        //輸出 0157.4200

String.Format("{0:(###) ###-####}", 8005551212) //輸出 (800) 555-1212

String.Format("{0:0,0}", 38560)                                   //輸出 38,560

String.Format("{0:0%}", 0.283333)                              //輸出28%
String.Format("{0:0.00%}",0.283333);                         // 輸出 28.33%

String.Format("{0:$#,##0.00;($#,##0.00);Zero}", 0) //輸出 Zero
String.Format("{0:$#,##0.00;($#,##0.00);Zero}", 1243.50) //輸出 $1,243.50

3.Dates日期格式化
--1.基本的日期格式化字符

字符	類型	示例 (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

--2.自定義日期格式

字符	類型	示例	輸出
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

 4.Enumerations枚舉格式化

字符	類型
g	Default (Flag names if available, otherwise decimal)
f	Flags always
d	Integer always
x	Eight digit hex.

本文參考資料:http://blog.stevex.net/index.php/string-formatting-in-csharp/