Why won't this Path.Combine work? [duplicate]

This question already has answers here: Why does Path.Combine not properly concatenate filenames that start with Path.DirectorySeparatorChar? 开发者_运维百科 (16 answers) Closed 9 years ago.

I have the following command:

string reportedContentFolderPath =
Path.Combine(contentFolder.FullName.ToString(), @"\ReportedContent\");

When I look in the debugger I can see the following:

contentFolder.FullName = "E:\\"

However

reportedContentFolderPath = "\\ReportedContent\\"

Why is the Path.Combine chopping off the E:\?

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You have a leading slash on @"\ReportedContent\". You don't want that (or the trailing one, I suspect) - try just:

string reportedContentFolderPath =
    Path.Combine(contentFolder.FullName.ToString(), "ReportedContent");

From the documentation:

If path2 does not include a root (for example, if path2 does not start with a separator character or a drive specification), the result is a concatenation of the two paths, with an intervening separator character. If path2 includes a root, path2 is returned.

In your case, path2 did contain a root, so it was returned without looking at path1.

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It is explained in the method documentation:

If path2 does not include a root (for example, if path2 does not start with a separator character or a drive specification), the result is a concatenation of the two paths, with an intervening separator character. If path2 includes a root, path2 is returned.

I recommend you read it all to understand how all the possible combinations work out: Path.Combine Method

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Path.Combine will return the second argument if it begins with a separation character (\).

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I'd bet that by specifying the slash as prefix in the second string, the Combine method assumes the current drive. Try to remove the slash.

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From MSDN (emphasis mine):

public static string Combine(string path1, string path2)

[...]

Return Value

Type: System.String The combined paths. If one of the specified paths is a zero-length string, this method returns the other path. If path2 contains an absolute path, this method returns path2.

@"\ReportedContent\" is an absolute path because it begins with a backslash.

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It looks like Path.Combine thinks the two slashes E:\\ refers to a UNC path, and a UNC path should not be prefixed with a drive letter. Change the contentFolder to E:\ and it should work.