IFormattable::ToString Method
Formats the value of the current instance using the specified format.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- format
- Type: System::String
The format to use.
-or-
A null reference (Nothing in Visual Basic) to use the default format defined for the type of the IFormattable implementation.
- formatProvider
- Type: System::IFormatProvider
The provider to use to format the value.
-or-
A null reference (Nothing in Visual Basic) to obtain the numeric format information from the current locale setting of the operating system.
The ToString method converts a value to a string representation that can be expressed in multiple ways. Its precise format depends on specific symbols or a specified order defined by specific cultures, professions, or industries. You can call the method directly. It is also called automatically by the Convert::ToString(Object) and Convert::ToString(Object, IFormatProvider) methods, and by methods that use the composite formatting feature in the .NET Framework, such as String::Format(String, array<Object>), Console::WriteLine(String, array<Object>), and StringBuilder::AppendFormat(String, array<Object>).(For more information, see Composite Formatting.)
Composite formatting methods call the ToString method once for each format item in a format string. The parameters passed to the method depend on the specific formatting method that is called and on the content of the format item, as follows:
If the format item does not include a format string (for example, if the format item is simply {0}), it is passed nullptr as the value of the System::String parameter.
If the format item includes a format string (for example, {0:G}), that format string is passed as the value of the System::String parameter.
If the original method call does not include an System::IFormatProvider parameter, CultureInfo::CurrentCulture is passed as the value of the System::IFormatProvider parameter.
If the original method call includes an System::IFormatProvider parameter, the provider that is supplied in the method call is passed as the value of the System::IFormatProvider parameter.
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An object's ToString implementation is called by composite formatting methods only if they are not passed an ICustomFormatter format provider, or if the Format method of the custom format provider returns nullptr. |
The .NET Framework includes three format providers, all of which implement the IFormatProvider interface:
NumberFormatInfo supplies numeric formatting information, such as the characters to use for decimal and group separators, and the spelling and placement of currency symbols in monetary values.
DateTimeFormatInfo supplies date-related and time-related formatting information, such as the position of the month, the day, and the year in a date pattern.
CultureInfo contains the default formatting information in a specific culture, including the numeric format information, and date-related and time-related formatting information.
In addition, you can define your own custom format provider.
Notes to ImplementersThe ToString method must support the "G" (general) format specifier. Besides the "G" specifier, the class can define the list of format specifiers that it supports. In addition, the class must be prepared to handle a format specifier that is nullptr. For more information about formatting and formatting codes, see Formatting Types
The following example demonstrates a Temperature class that implements the ToString method. This code example is part of a larger example provided for the IFormattable class.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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