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

C 或 c
货币
Console.Write("{0:C}", 2.5); / 2.50
Console.Write("{0:C}", -2.5); //($2.50)

D 或 d
十进制数
Console.Write("{0:D5}", 25); //00025

E 或 e
科学型
Console.Write("{0:E}", 250000); //2.500000E+005

F 或 f
固定点
Console.Write("{0:F2}", 25); //25.00
Console.Write("{0:F0}", 25); //25

G 或 g
常规
Console.Write("{0:G}", 2.5); //2.5

N 或 n
数字
Console.Write("{0:N}", 2500000); //2,500,000.00

X 或 x
十六进制
Console.Write("{0:X}", 250); //FA
Console.Write("{0:X}", 0xffff); //FFFF

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C#格式化数值结果表

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.

Numbers

Basic number formatting specifiers:

Custom number formatting:

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.

The 'U' specifier seems broken; that string certainly isn't sortable.

Custom date formatting:

Enumerations

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%