c++ - C# Pointer: error CS0254: The right hand side of a fixed statement assignment may not be a cast expression -

i have c++ server , trying make c# client.

in c++, send packet make this:

pmessage *msg = (pmessage*)&buf[0]; msg->id = pid_login; sendto(sserver, buf, sizeof(buf), 0, (sockaddr*)&from, fromlen); 

in c# trying this:

unsafe {     try     {         byte[] rawdata = new byte[marshal.sizeof(typeof(pmessage))];          fixed (pmessage* p = (pmessage*)&rawdata[0])         {          //     p->id = 1001;         }         udpclient.send(rawdata, rawdata.length); ;     }     catch (exception ex)     {         messagebox.show(ex.tostring());     } } 

the compiler show error:

error cs0254: right hand side of fixed statement assignment may not cast expression.

c#:

[structlayout(layoutkind.sequential, pack = 1)]  unsafe struct pmessage {     public  fixed byte msg[256];     public int id;     public int size; } 

c++:

   struct pmessage     {         char msg[256];         unsigned int id;         unsigned int size;     }; 

you can't this, because compiler loses track of object needs pinned.

fixed (pmessage* p = (pmessage*)&rawdata[0]) 

however should work

fixed (byte* pby = &rawdata[0]) {     pmessage* p = (pmessage*)pby; 

please note c++ code violating strict aliasing, , both c++ , c# may not have correct alignment.