Windows system casting

[Alexander Patapoff via Digitalmars-d-learn]

import std.stdio;
import std.string;
import core.sys.windows.windows;
void main() {
	
	string filepath = 
"C:\\Users\\awpat\\Pictures\\patterns_00387591.jpg";
	auto p = toStringz(filepath);

	int result;
	result = SystemParametersInfo(cast(uint)SPI_SETDESKWALLPAPER, 
cast(uint)0, cast(void*)p ,cast(uint)SPIF_UPDATEINIFILE);
	
}

I'm trying to change the background of my computer. to do this I 
must convert my string to a const char*, then that can implicitly 
to a (PVOID). I believe that I am losing all my data in the 
casting process, is there a way for me to keep my data? or if I 
am casting this improperly can you demonstrate and explain the 
proper way to cast to a void pointer (PVOID)?


thanks!!