ToString()的标准格式化字符串分为3大类：枚举类型的格式化字符串，数值类型的格式化字符串，和日期时间类型的格式化字符串。
日期时间类型的格式化字符串请见我的博客DateTime格式字符串。
Enumeration Format Strings
|
Format string |
Result |
|---|---|
|
G or g |
Displays the enumeration entry as a string value, if possible, and otherwise displays the integer value of the current instance. If the enumeration is defined with the Flags attribute set, the string values of each valid entry are concatenated together, separated by commas. If the Flags attribute is not set, an invalid value is displayed as a numeric entry. The following example illustrates the G format specifier. C#
Console.WriteLine(ConsoleColor.Red.ToString("G")); // Displays Red FileAttributes attributes = FileAttributes.Hidden | FileAttributes.Archive; Console.WriteLine(attributes.ToString("G")); // Displays Hidden, Archive |
|
F or f |
Displays the enumeration entry as a string value, if possible. If the value can be completely displayed as a summation of the entries in the enumeration (even if the Flags attribute is not present), the string values of each valid entry are concatenated together, separated by commas. If the value cannot be completely determined by the enumeration entries, then the value is formatted as the integer value. The following example illustrates the F format specifier. C#
Console.WriteLine(ConsoleColor.Blue.ToString("F")); // Displays Blue FileAttributes attributes = FileAttributes.Hidden | FileAttributes.Archive; Console.WriteLine(attributes.ToString("F")); // Displays Hidden, Archive |
|
D or d |
Displays the enumeration entry as an integer value in the shortest representation possible. The following example illustrates the D format specifier. C#
Console.WriteLine(ConsoleColor.Cyan.ToString("D")); // Displays 11 FileAttributes attributes = FileAttributes.Hidden | FileAttributes.Archive; Console.WriteLine(attributes.ToString("D")); // Displays 34 |
|
X or x |
Displays the enumeration entry as a hexadecimal value. The value is represented with leading zeros as necessary, to ensure that the value is a minimum eight digits in length. The following example illustrates the X format specifier. C#
Console.WriteLine(ConsoleColor.Cyan.ToString("X")); // Displays 0000000B FileAttributes attributes = FileAttributes.Hidden | FileAttributes.Archive; Console.WriteLine(attributes.ToString("X")); // Displays 00000022 |
Standard Numeric Format Strings
|
Format specifier |
Name |
Description |
Examples |
|---|---|---|---|
|
"C" or "c" |
Currency |
Result: A currency value. Supported by: All numeric types. Precision specifier: Number of decimal digits. Default precision specifier: Defined by NumberFormatInfo. More information: The Currency ("C") Format Specifier. |
123.456 ("C", en-US) -> $123.46 123.456 ("C", fr-FR) -> 123,46 € 123.456 ("C", ja-JP) -> ¥123 -123.456 ("C3", en-US) -> ($123.456) -123.456 ("C3", fr-FR) -> -123,456 € -123.456 ("C3", ja-JP) -> -¥123.456 |
|
"D" or "d" |
Decimal |
Result: Integer digits with optional negative sign. Supported by: Integral types only. Precision specifier: Minimum number of digits. Default precision specifier: Minimum number of digits required. More information: The Decimal("D") Format Specifier. |
1234 ("D") -> 1234 -1234 ("D6") -> -001234 |
|
"E" or "e" |
Exponential (scientific) |
Result: Exponential notation. Supported by: All numeric types. Precision specifier: Number of decimal digits. Default precision specifier: 6. More information: The Exponential ("E") Format Specifier. |
1052.0329112756 ("E", en-US) -> 1.052033E+003 1052.0329112756 ("e", fr-FR) -> 1,052033e+003 -1052.0329112756 ("e2", en-US) -> -1.05e+003 -1052.0329112756 ("E2", fr_FR) -> -1,05E+003 |
|
"F" or "f" |
Fixed-point |
Result: Integral and decimal digits with optional negative sign. Supported by: All numeric types. Precision specifier: Number of decimal digits. Default precision specifier: Defined by NumberFormatInfo. More information: The Fixed-Point ("F") Format Specifier. |
1234.567 ("F", en-US) -> 1234.57 1234.567 ("F", de-DE) -> 1234,57 1234 ("F1", en-US) -> 1234.0 1234 ("F1", de-DE) -> 1234,0 -1234.56 ("F4", en-US) -> -1234.5600 -1234.56 ("F4", de-DE) -> -1234,5600 |
|
"G" or "g" |
General |
Result: The most compact of either fixed-point or scientific notation. Supported by: All numeric types. Precision specifier: Number of significant digits. Default precision specifier: Depends on numeric type. More information: The General ("G") Format Specifier. |
-123.456 ("G", en-US) -> -123.456 123.456 ("G", sv-SE) -> -123,456 123.4546 ("G4", en-US) -> 123.5 123.4546 ("G4", sv-SE) -> 123,5 -1.234567890e-25 ("G", en-US) -> -1.23456789E-25 -1.234567890e-25 ("G", sv-SE) -> -1,23456789E-25 |
|
"N" or "n" |
Number |
Result: Integral and decimal digits, group separators, and a decimal separator with optional negative sign. Supported by: All numeric types. Precision specifier: Desired number of decimal places. Default precision specifier: Defined by NumberFormatInfo. More information: The Numeric ("N") Format Specifier. |
1234.567 ("N", en-US) -> 1,234.57 1234.567 ("N", ru-RU) -> 1 234,57 1234 ("N", en-US) -> 1,234.0 1234 ("N", ru-RU) -> 1 234,0 -1234.56 ("N", en-US) -> -1,234.560 -1234.56 ("N", ru-RU) -> -1 234,560 |
|
"P" or "p" |
Percent |
Result: Number multiplied by 100 and displayed with a percent symbol. Supported by: All numeric types. Precision specifier: Desired number of decimal places. Default precision specifier: Defined by NumberFormatInfo. More information: The Percent ("P") Format Specifier. |
1 ("P", en-US) -> 100.00 % 1 ("P", fr-FR) -> 100,00 % -0.39678 ("P1", en-US) -> -39.7 % -0.39678 ("P1", fr-FR) -> -39,7 % |
|
"R" or "r" |
Round-trip |
Result: A string that can round-trip to an identical number. Supported by: Single, Double, and BigInteger. Precision specifier: Ignored. More information: The Round-trip ("R") Format Specifier. |
123456789.12345678 ("R") -> 123456789.12345678 -1234567890.12345678 ("R") -> -1234567890.1234567 |
|
"X" or "x" |
Hexadecimal |
Result: A hexadecimal string. Supported by: Integral types only. Precision specifier: Number of digits in the result string. More information: The HexaDecimal ("X") Format Specifier. |
255 ("X") -> FF -1 ("x") -> ff 255 ("x4") -> 00ff -1 ("X4") -> 00FF |
|
Any other single character |
Unknown specifier |
Result: Throws a FormatException at run time. |