C# Command-Line Parsing of Quoted Paths and Avoiding Escape Characters

Question

How is it possible to parse command-line arguments that are to be interpreted as paths? args[] contains strings that are automatically joined if they are quoted, e.g.:

Answer 1

I had the same frustration. My solution was to use regular expressions. My expected input is a list of paths, some of which may be quoted. The above kludge doesn't work unless all the last arguments are quoted.

// Capture quoted string or non-quoted strings followed by whitespace
string exp = @"^(?:""([^""]*)""\s*|([^""\s]+)\s*)+";
Match m = Regex.Match(Environment.CommandLine, exp);

// Expect three Groups
// group[0] = entire match
// group[1] = matches from left capturing group
// group[2] = matches from right capturing group
if (m.Groups.Count < 3)
    throw new ArgumentException("A minimum of 2 arguments are required for this program");

// Sort the captures by their original postion
var captures = m.Groups[1].Captures.Cast<Capture>().Concat(
               m.Groups[2].Captures.Cast<Capture>()).
               OrderBy(x => x.Index).
               ToArray();

// captures[0] is the executable file
if (captures.Length < 3)
    throw new ArgumentException("A minimum of 2 arguments are required for this program");

Can anyone see a more efficient regex?

Answer 2

I like your idea:

_path = args[i].Replace("\"", @"\");

It is clean, and will have no effect unless the problem exists.

Answer 3

Not an answer, but here's some background and explanation from Jeffrey Tan, Microsoft Online Community Support (12/7/2006):

Note: this is not not a code defeat but by design, since backslashe are normally used to escape certain special character. Also, this algorithm is the same as Win32 command line arguments parsing function CommandLineToArgvW. See the Remarks section below: http://msdn2.microsoft.com/en-us/library/bb776391.aspx

Also makes reference to the FX method Environment.GetCommandLineArgs for further explanation of the slash handling behavior.

Personally I think this is a drag, and I'm surprised I haven't been bit by it before. Or maybe I have and don't know it? Blind replacement of quotes with slashes doesn't strike me as a solution, though. I'm voting the question up, because it was an eye opener.