String.Format usage in C #

Tring. Several definitions of the Format method:

String.Format (String, Object) replaces the format item in the specified String with the text equivalent of the value of the specified Object instance.
String.Format (String, object[]) replaces the format item in the specified string with the text equivalent of the value of the corresponding Object instance in the specified array.
String.Format (IFormatProvider, String, object[]) replaces the format item in the specified string with the text equivalent of the value of the corresponding Object instance in the specified array. The specified parameter provides culture-specific formatting information.
String.Format (String, Object, object) replaces the format item in the specified string with the text equivalent of a value of two specified Object instance.
String.Format (String, Object, object, object) replaces the format item in the specified string with the text equivalent of a value of three specified Object instance.

Commonly used formatted numeric results table

Character	Description	Example	Output
C	Currency	string. Format("{0:c3}", 2)	$2.000
D	Decimal	string. Format("{0:d3}", 2)	002
E	Scientific counting method	1.20E+001	1.20E+001
G	Conventional	string. Format("{0:g}", 2)	2
N	Numbers separated by semicolons	string. Format("{0:n}", 250000)	250,000.00
X	Hexadecimal	string. Format("{0:x000}", 12)	C
		string. Format("{0:000.000}", 12.2)	012.200

Several examples of common use

1. Number format for strings

1234567

stringstr1 =string.Format("{0:N1}",56789);               //result: 56,789.0stringstr2 =string.Format("{0:N2}",56789);               //result: 56,789.00stringstr3 =string.Format("{0:N3}",56789);               //result: 56,789.000stringstr8 =string.Format("{0:F1}",56789);               //result: 56789.0stringstr9 =string.Format("{0:F2}",56789);               //result: 56789.00stringstr11 =(56789 / 100.0).ToString("#.##");           //result: 567.89stringstr12 =(56789 / 100).ToString("#.##");             //result: 567

2. Formatted currency (related to system environment, Chinese system default format RMB, English system format USD)

1	string.Format("{0:C}",0.2)

　　

The result is: ￥0.20 (English operating system results: $0.20)

The default formatting retains two decimal places after the decimal point, and if you need to keep one or more, you can specify the number of digits

1	string.Format("{0:C1}",23.15)

　　

The result is: ￥23.2 (intercept will be automatically rounded)
Formatting multiple instances of object

1	string.Format("市场价：{0:C}，优惠价{1:C}",23.15,19.82)

3, formatted decimal number (formatted as a fixed number of digits, the number of digits can not be less than unformatted before, only support shaping)

12	string.Format("{0:D3}",23) //结果为：023string.Format("{0:D2}",1223) //结果为：1223，（精度说明符指示结果字符串中所需的最少数字个数。）

　　

4. A semicolon-delimited number, and specify the number of digits after the decimal point

12	string.Format("{0:N}", 14200) //结果为：14,200.00 （默认为小数点后面两位）string.Format("{0:N3}", 14200.2458) //结果为：14,200.246 （自动四舍五入）

5. Percentage of formatting

12	string.Format("{0:P}", 0.24583) //结果为：24.58% （默认保留百分的两位小数）string.Format("{0:P1}", 0.24583) //结果为：24.6% （自动四舍五入）

6, zero placeholder and digit placeholder

1234	string , 12394.039)   //result: 12394.04 string , 194.039)   //result: 0194.04 string , 12394.039)   //result: 12394.04 string , 194.039)   //result: 194

　　

The following explanation is difficult to understand, more test the actual application can be understood.
Zero placeholder: If a formatted value has a number in the format string where "0" appears, this number is copied to the result string. The position of the leftmost "0" before the decimal point and the rightmost "0" after the decimal point determine the total number range that appears in the result string. The "00" specifier causes the value to be rounded to the nearest digit before the decimal point, where 0 bits are always removed.
Digit placeholder: If the formatted value has a number in the format string where "#" appears, this number is copied to the result string. Otherwise, no value is stored at this location in the resulting string.
Note that if "0" is not a valid number, this specifier never displays the "0" character, even if "0" is the only number in the string. If "0" is a valid number in the displayed number, the "0" character is displayed. The "# #" format string allows the value to be rounded to the nearest digit before the decimal point, where 0 is always removed.

7. Date formatting

123456789

string.Format("{0:d}",System.DateTime.Now) //结果为：2009-3-20 （月份位置不是03）string.Format("{0:D}",System.DateTime.Now) //结果为：2009年3月20日string.Format("{0:f}",System.DateTime.Now) //结果为：2009年3月20日 15:37 string.Format("{0:F}",System.DateTime.Now) //结果为：2009年3月20日 15:37:52 string.Format("{0:g}",System.DateTime.Now) //结果为：2009-3-20 15:38 string.Format("{0:G}",System.DateTime.Now) //结果为：2009-3-20 15:39:27 string.Format("{0:m}",System.DateTime.Now) //结果为：3月20日string.Format("{0:t}",System.DateTime.Now) //结果为：15:41 string.Format("{0:T}",System.DateTime.Now) //结果为：15:41:50

　　

String.Format usage in C #