C# Signature:

[DllImport("shell32.dll", SetLastError = true)]
[DllImport("shell32.dll")]
static extern IntPtr CommandLineToArgvW(
   [MarshalAs(UnmanagedType.LPWStr)] string lpCmdLine,
   out int pNumArgs);
   [MarshalAs(UnmanagedType.LPWStr)] string lpCmdLine, out int pNumArgs);

VB.NET Signature:

Declare Function CommandLineToArgv Lib "shell32.dll" Alias "CommandLineToArgvW" ( _
    ByVal lpCmdLine As String, _
    ByRef pNumArgs As Integer) As Long

User-Defined Types:

None.

Notes:

Tips & Tricks:

Please add some!

Sample Code:

using System;
using System.Runtime.InteropServices;
using System.Text;

static class CmdLineToArgvW
namespace CmdLineToArgvW
{
    // The previous examples on this page used incorrect
    // pointer logic and were removed.

    static string[] SplitArgs(string unsplitArgumentLine)
    class MainModule
    {
        int numberOfArgs;
        IntPtr ptrToSplitArgs;
        string[] splitArgs;

        ptrToSplitArgs = CommandLineToArgvW(unsplitArgumentLine, out numberOfArgs);

        // CommandLineToArgvW returns NULL upon failure.
        if (ptrToSplitArgs == IntPtr.Zero)
            throw new ArgumentException("Unable to split argument.", new Win32Exception());

        // Make sure the memory ptrToSplitArgs to is freed, even upon failure.
        try
        static void Main(string[] args)
        {
            splitArgs = new string[numberOfArgs];
            Console.WriteLine( "args.Length: {0}", args.Length );
            for ( int i = 0; i < args.Length; i++ )
            {
                Console.WriteLine( "args[{0}]={1}", i, args[i] );
            }

            // ptrToSplitArgs is an array of pointers to null terminated Unicode strings.
            // Copy each of these strings into our split argument array.
            for (int i = 0; i < numberOfArgs; i++)
                splitArgs[i] = Marshal.PtrToStringUni(
                    Marshal.ReadIntPtr(ptrToSplitArgs, i * IntPtr.Size));
            Console.WriteLine();

            return splitArgs;
        }
        finally
        {
            // Free memory obtained by CommandLineToArgW.
            LocalFree(ptrToSplitArgs);
        }
    }
            int argc;
            IntPtr argvPtr = IntPtr.Zero;
            try
            {
                argvPtr = CommandLineToArgvW( Environment.CommandLine, out argc );
                // CommandLineToArgvW will list the executable as argv[0].
                // I want to see the same count as you get from "string[] args".
                Console.WriteLine( "argc: {0}", argc - 1 );

    [DllImport("shell32.dll", SetLastError = true)]
    static extern IntPtr CommandLineToArgvW(
        [MarshalAs(UnmanagedType.LPWStr)] string lpCmdLine,
        out int pNumArgs);
                // argvPtr is a pointer to a pointer; dereference it
                IntPtr argPtr = Marshal.ReadIntPtr( argvPtr );

    [DllImport("kernel32.dll")]
    static extern IntPtr LocalFree(IntPtr hMem);
}
                for ( int i = 0; i < argc; i++ )
                {
                    string arg = Marshal.PtrToStringUni( argPtr );

                    // CommandLineToArgvW will list the executable as argv[0].
                    // I want to get the same output that "string[] args" yields,
                    // so I'll skip the output for i = 0
                    if ( i > 0 )
                    {
                        Console.WriteLine( "argv[{0}]={1}", i - 1, arg );
                    }

                    // Increment the pointer address by the number of Unicode bytes
                    // plus one Unicode character for the string's null terminator
                    int unicodeByteCount =
                        Encoding.Unicode.GetByteCount( arg ) +
                        Encoding.Unicode.GetByteCount( new char[] { Char.MinValue } );
                    argPtr = new IntPtr( argPtr.ToInt32() + unicodeByteCount );
                }

Alternative Managed API:

Do you know one? Please contribute it!

            }
            finally
            {
                LocalFree( argvPtr );
            }

        }

        // Here's an wrapper to CommandLineToArgvW I found useful (csells@sellsbrothers.com)
        public static IEnumerable<string> CommandLineToExeAndArgs() {
            return CommandLineToExeAndArgs(Environment.CommandLine);
        }

        public static IEnumerable<string> CommandLineToExeAndArgs(string cmdline) {
            List<string> args = new List<string>();
            IntPtr argvPtr = IntPtr.Zero;

            try {
                int argc;
                argvPtr = CommandLineToArgvW(cmdline, out argc);

                // argvPtr is a pointer to a pointer; dereference it
                IntPtr argPtr = Marshal.ReadIntPtr(argvPtr);

                // CommandLineToArgvW will list the executable as argv[0]
                for( int i = 0; i < argc; i++ ) {
                    string arg = Marshal.PtrToStringUni(argPtr);
                    args.Add(arg);

                    // Increment the pointer address by the number of Unicode bytes
                    // plus one Unicode character for the string's null terminator
                    int unicodeByteCount = Encoding.Unicode.GetByteCount(arg) + Encoding.Unicode.GetByteCount(new char[] { Char.MinValue });
                    argPtr = new IntPtr(argPtr.ToInt32() + unicodeByteCount);
                }
            }
            finally {
                LocalFree(argvPtr);
            }

            return args;
        }

        [DllImport("shell32.dll")]
        static extern IntPtr CommandLineToArgvW(
            [MarshalAs(UnmanagedType.LPWStr)] string lpCmdLine,
            out int pNumArgs);

        [DllImport("kernel32.dll")]
        static extern IntPtr LocalFree(IntPtr hMem);
    }
}

Alternative Managed API:

Do you know one? Please contribute it!

On Windows Vista:

This API no longer works on windows Vista as Microsoft disabled it for security reasons. See http://msdn2.microsoft.com/en-us/library/ms647840.aspx.

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