ChangeExtension Method

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Changes the extension of a path string.

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

public static string ChangeExtension(
	string path,
	string extension
)

Parameters

path
Type: System..::..String
The path information to modify. The path cannot contain any of the characters defined in GetInvalidPathChars.
extension
Type: System..::..String
The new extension (with or without a leading period). Specify nullNothingnullptrunita null reference (Nothing in Visual Basic) to remove an existing extension from path.

Return Value

Type: System..::..String
The modified path information.

If neither path nor extension contains a period (.), ChangeExtension adds the period.

The extension parameter can contain multiple periods and any valid path characters, and can be any length. If extension is nullNothingnullptrunita null reference (Nothing in Visual Basic), the returned string contains the contents of path with the last period and all characters following it removed.

If extension is an empty string, the returned path string contains the contents of path with any characters following the last period removed.

If path does not have an extension and extension is not nullNothingnullptrunita null reference (Nothing in Visual Basic), the returned string contains path followed by extension.

If extension is not nullNothingnullptrunita null reference (Nothing in Visual Basic) and does not contain a leading period, the period is added.

If path contains a multiple extension separated by multiple periods, the returned string contains the contents of path with the last period and all characters following it replaced by extension. For example, if path is "\Dir1\examples\pathtests.csx.txt" and extension is "cs", the modified path is "\Dir1\examples\pathtests.csx.cs".

It is not possible to verify that the returned results are valid in all scenarios. For example, if path is empty, extension is appended.

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