CsWin32 how to create an instance of PWSTR for e.g. GetWindowText

Question

I just started using CsWin32 and one of the Win32 functions I want to use it GetWindowText which gets mapped to I know how to work with the first and last parameter, but I don't know what to do with the one in the middle, the PWSTR lpString. How do I create an instance of that? The source code for PWSTR looks like this (excerpt):

internal unsafe readonly partial struct PWSTR
    : IEquatable<PWSTR>
{
    // ...
    internal PWSTR(char* value) => this.Value = value;
    // ...
}

Guess I have to so something like

PWSTR lpString = new PWSTR(<what to do here>);

but I don't know how to create a char* or equivalent in C# ?

Answer 1

Try using pointers. You have to use unsafe and fixed. Below is an example. Copied from a discussion (https://github.com/microsoft/CsWin32/discussions/181)

Not compiled and tested.

   int bufferSize = PInvoke.GetWindowTextLength(handle) + 1;
   unsafe // BELOW CODE INVOLVES POINTERS.
   {
       //ADDRESS WONT CHANGE, THIS VARIABLE SHOULD BE USED WITH IN THIS SCOPE.
       fixed (char* windowNameChars = new char[bufferSize]) 
       {
           if (PInvoke.GetWindowText(handle, windowNameChars, bufferSize) == 0)
           {
               int errorCode = Marshal.GetLastWin32Error();
               if (errorCode != 0)
               {
                   throw new Win32Exception(errorCode);
               }

               return true;
           }

           string windowName = new string(windowNameChars);
       }

       return true;
   }