Guid.ToString Method (String, IFormatProvider)


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Returns a string representation of the value of this instance of the Guid class, according to the provided format specifier and culture-specific format information.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

public string ToString(
	string format,
	IFormatProvider provider


Type: System.String

A single format specifier that indicates how to format the value of this Guid. The format parameter can be "N", "D", "B", "P", or "X". If format is null or an empty string (""), "D" is used.

Type: System.IFormatProvider

(Reserved) An object that supplies culture-specific formatting information.

Return Value

Type: System.String

The value of this Guid, represented as a series of lowercase hexadecimal digits in the specified format.

Exception Condition

The value of format is not null, an empty string (""), "N", "D", "B", "P", or "X".

The provider parameter is reserved for future use and does not contribute to the execution of this method. You can pass null in the method call.

The following table shows the accepted format specifiers for the format parameter. "0" represents a digit; hyphens ("-"), braces ("{", "}"), and parentheses ("(", ")") appear as shown.


Format of return value


32 digits:



32 digits separated by hyphens:



32 digits separated by hyphens, enclosed in braces:



32 digits separated by hyphens, enclosed in parentheses:



Four hexadecimal values enclosed in braces, where the fourth value is a subset of eight hexadecimal values that is also enclosed in braces:


The hexadecimal digits a through f are lowercase in the returned string. To convert them to uppercase, call the String.ToUpper method on the returned string.

Because the provider parameter is ignored, you cannot use it to provide a custom formatting solution. To represent a Guid value as a string in a format that isn't supported by the standard GUID format strings, call the String.Format(IFormatProvider, String, Object[]) method with a provider object that implements both the ICustomFormatter and IFormatProvider interfaces. For more information, see the "Custom Formatting with ICustomFormatter" section in the Formatting Types article.

.NET Framework
Available since 1.1
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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