[Mono-dev] String comparison failing between C# and C

[Dan Osawa]

Hello,

I'm currently testing Mono's interoperability between C# and C code, and
have run into an interesting scenario.



In my test case I have a C shared object that implements two functions:
setString and getString.  The first function, setString, simply copies the
string into a local buffer.  The second function, getString, returns a
pointer to the internal buffer holding the string.



What's interesting is that the first case (in the below C# code) fails when
it tries to compare "hello" against the return value of getString.  Is this
a problem with trying to compare a unicode string with an ansi string?  This
test case passes when running under Windows via CLR...fails in Linux via
Mono.



The second case, "hello" == s, passes.



namespace MonoEvaluation.Interop

{

    public class Tester : ITester

    {

        [DllImport("InteropServerDllC")]

        static extern void setString(string s);



        [DllImport("InteropServerDllC")]

        static extern string getString();



        bool StringTest()

        {

            setString("hello");

            string s = getString();





            if ("hello" == getString())

            {

                Console.WriteLine("hello == getString passed!");

            }

            else

{

    Console.WriteLine("hello == getString failed!");

    return false;

}



            if (("hello"  == s)

            {

                Console.WriteLine("hello == s passed!");

            }

            else

{

    Console.WriteLine("hello == s failed!");

    return false;

}

return true;

        }



    }

}



I'm running this on an embedded PPC Arabella Linux system, using mono
version 1.2.5.1.



Thanks in Advance,

Dan
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