.NET2 Test if a string is a valid path

Question

.NET methods like Path.IsPathRooted() are great, but throw if the input string isn't valid. Which is fine, but it would be nice to pre-check if an input string is a valid path before jumping into an exception-checking codeblock.

I can't see a Path.IsValidPath() or similar, is there something like this available?

Valid as in "path exists" or in "path conforms to formal criteria"? — Daniel Hilgarth, Feb 08 '13 at 15:13
Valid as it will it throw an exception with the `Path` methods :) — Mr. Boy, Feb 08 '13 at 15:16
@Ani I don't think this is quite the same question - surely some valid URIs would cause an Exception in `Path.IsRooted()` for example? — Mr. Boy, Feb 08 '13 at 15:18

score 1 · Answer 1 · answered Feb 08 '13 at 15:16

According to the documentation,

ArgumentException [is thrown when] path contains one or more of the invalid characters defined in GetInvalidPathChars.

This means that you can pre-validate your path strings as follows:

if (path.IndexOfAny(Path.GetInvalidPathChars()) != -1) {
    // This means that Path.IsPathRooted will throw an exception
    ....
}

This is the only condition under which IsPathRooted throws an exception.

Take a look at Mono source of Path.cs, line 496, for details on how this is implemented.

Tim Schmelter · Answer 2 · 2013-02-11T14:31:20.467

1

You could use File.Exists or Directory.Exists.

If you want to check if a path contains illegal chars (on NET 2.0) you can use Path.GetInvalidPathChars:

char[] invalidChars = System.IO.Path.GetInvalidPathChars();
bool valid = path.IndexOfAny(invalidChars) != -1;

edited Feb 11 '13 at 14:31

answered Feb 08 '13 at 15:17

Tim Schmelter

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score 0 · Answer 3 · answered Feb 08 '13 at 15:18

public bool ValidPathString(string path)
{
    if (string.IsNullOrEmpty(path)) return false;
    char[] invalidPathChars = System.IO.Path.GetInvalidPathChars();
    foreach (char c in invalidPathChars)
    {
        if(path.Contains(c)) return false;
    }
    return true;
}

.NET2 Test if a string is a valid path

3 Answers3