Unable to Find my Native DLL (Error Code 0x8007007E)

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C#

marshalling

Hello Experts,

I have created a Native Dll (myNativeDll.dll) just to keep it simple it exposes one method.

__declspec(dllexport)char * GetStringFromDll( )
{

const size_t alloc_size = 128;
STRSAFE_LPSTR result = (STRSAFE_LPSTR)CoTaskMemAlloc( alloc_size );
STRSAFE_LPCSTR retstr = "This value is returned from native dll";
StringCchCopyA( result, alloc_size, retstr );
return (char *) result;
}

on the client side (Managed App) defined a helper class to use this dll as

namespace MarshalStringApp
{
    public class MyDllWrapper
    {
        //  Calling Standard Windows Functions.
        [DllImport("User32.dll", EntryPoint = "MessageBox", CharSet = CharSet.Auto)]
        public static extern int MsgBox(int hWnd, String text, String caption, uint type);

        //  Calling Functions from our Dll.
        [DllImport("myNativeDll.dll")]
        public static extern String GetStringFromDll();
    }
}

and added a handler to the form to call this function.

private void btnGetStringFromDll_Click(object sender, EventArgs e)
       {
           String str = "";
           try
           {
               str = MyDllWrapper.GetStringFromDll();
               MessageBox.Show("String Returned [" + str + "]");
           }
           catch (Exception eX)
           {
               MessageBox.Show(eX.Message);
           }
       }

I am getting an exception Code (0x8007007E), suggesting that DLL "myNativeDll.dll" is not found, i tried copying it to the client's folder to (where exe resides) but no avail. where should i copy this native dll, for this app to work. or i am missing something.

any help will be highly appreciated.

-prateek.