Console.WriteLine()函数中{}输出格式详解(C#)

 Console.WriteLine()函数的格式一直没怎么注意。今天同事问起Console.WriteLine({0:D3},a)的意义，忽然发现不知道D代表什么意义。以前以为{0,4}是指第一个变量输出时占8位，今天查了一下，发现也并不完全正确。

其中格式项都采用如下形式：

{index[,alignment][:formatString]}   

 

其中"index"指索引占位符，这个肯定都知道；

",alignment"按字面意思显然是对齐方式,以","为标记；

":formatString"就是对输出格式的限定，以":"为标记。

 

alignment:可选，是一个带符号的整数，指示首选的格式化字段宽度。如果“对齐”值小于格式化字符串的长度，“对齐”会被忽略，并且使用格式化字符串的长度作为字段宽度。如果“对齐”为正数，字段的格式化数据为右对齐；如果“对齐”为负数，字段的格式化数据为左对齐。如果需要填充，则使用空白。如果指定“对齐”，就需要使用逗号。

 

formatString:由标准或自定义格式说明符组成.

 

 下表是从网上得来：

字符

说明

示例

输出

C          货币string.Format("{0:C3}", 2)＄2.000D       十进制string.Format("{0:D3}", 2)002E    科学计数法1.20E+0011.20E+001G        常规string.Format("{0:G}", 2)2N 用分号隔开的数字string.Format("{0:N}", 250000)250,000.00X      十六进制string.Format("{0:X000}", 12)C  string.Format("{0:000.000}", 12.2)012.200

SpecifierTypeFormat Output
(Passed
Double 1.42)Output
(Passed
Int -12400)cCurrency{0:c}＄1.42-＄12,400dDecimal (Whole number){0:d}System.
FormatException-12400eScientific{0:e}1.420000e+000-1.240000e+004fFixed point{0:f}1.42-12400.00gGeneral{0:g}1.42-12400nNumber with commas for thousands{0:n}1.42-12,400rRound trippable{0:r}1.42System.
FormatExceptionxHexadecimal{0:x4}System.
FormatExceptioncf90
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
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

 

 

CSDN中例子：

 string myFName = "Fred";string myLName = "Opals";int myInt = 100;string FormatFName = String.Format("First Name = |{0,10}|", myFName);string FormatLName = String.Format("Last Name = |{0,10}|", myLName);string FormatPrice = String.Format("Price = |{0,10:C}|", myInt); Console.WriteLine(FormatFName);Console.WriteLine(FormatLName);Console.WriteLine(FormatPrice);FormatFName = String.Format("First Name = |{0,-10}|", myFName);FormatLName = String.Format("Last Name = |{0,-10}|", myLName);//-10指左对齐，10个宽度，FormatPrice = String.Format("Price = |{0,-10:C}|", myInt);//C指以货币形式输出Console.WriteLine(FormatFName);Console.WriteLine(FormatLName);Console.WriteLine(FormatPrice);//运行结果//First Name = | Fred|//Last Name = | Opals|//Price = | $100.00|//First Name = |Fred |//Last Name = |Opals |//Price = |$100.00 |

 

  还有其他事例见http://msdn.microsoft.com/en-us/library/aakt1eab.aspx