IPC C Example; A C example to send a search query to Everything using WM_COPYDATA and retrieve the results. Note: requires Everything running in the background.; https://www.voidtools.com/support/everything/sdk/ipc_c_example/

query.c

#define COPYDATA_QUERYCOMPLETE	0

BOOL sendquery(HWND hwnd,DWORD max_results,WCHAR *search_string,BOOL regex,BOOL match_case,BOOL match_whole_word,BOOL match_path)
{
	EVERYTHING_IPC_QUERY *query;
	DWORD len;
	DWORD size;
	HWND everything_hwnd;
	COPYDATASTRUCT cds;
	
	everything_hwnd = FindWindow(EVERYTHING_IPC_WNDCLASS,0);
	if (everything_hwnd)
	{
		len = (int)wcslen(search_string);
		
		size = sizeof(EVERYTHING_IPC_QUERY) - sizeof(WCHAR) + len*sizeof(WCHAR) + sizeof(WCHAR);
		
		query = (EVERYTHING_IPC_QUERY *)HeapAlloc(GetProcessHeap(),0,size);
		if (query)
		{
			query->max_results = max_results;
			query->offset = 0;
			query->reply_copydata_message = COPYDATA_QUERYCOMPLETE;
			query->search_flags = (regex?EVERYTHING_IPC_REGEX:0) | (match_case?EVERYTHING_IPC_MATCHCASE:0) | (match_whole_word?EVERYTHING_IPC_MATCHWHOLEWORD:0) | (match_path?EVERYTHING_IPC_MATCHPATH:0);
			query->reply_hwnd = hwnd;
			
			CopyMemory(query->search_string,search_string,(len+1)*sizeof(WCHAR));
			
			cds.cbData = size;
			cds.dwData = EVERYTHING_IPC_COPYDATAQUERY;
			cds.lpData = query;
			
			if (SendMessage(everything_hwnd,WM_COPYDATA,(WPARAM)hwnd,(LPARAM)&cds) == TRUE)
			{
				HeapFree(GetProcessHeap(),0,query);
				
				return TRUE;
			}
			else
			{
				// Everything IPC service not running
			}
			
			HeapFree(GetProcessHeap(),0,query);
		}
	}
	else
	{
		// the everything window was not found.
		// we can optionally RegisterWindowMessage("EVERYTHING_IPC_CREATED") and 
		// wait for Everything to post this message to all top level windows when its up and running.
	}
	
	return FALSE;
}

usage.c

void DisplayPathName(TCHAR *path,TCHAR *filename)
{
	// ...
	// do something with path and filename
	// ...
}

LRESULT CALLBACK window_proc(HWND hwnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
	DWORD i;
	EVERYTHING_IPC_LIST *list
	
	switch(uMsg)
	{
		case WM_COPYDATA:
		{
			COPYDATASTRUCT *cds = (COPYDATASTRUCT *)lParam;
			
			switch(cds->dwData)
			{
				case COPYDATA_QUERYCOMPLETE:
				
				list = (EVERYTHING_IPC_LIST *)cds->lpData;
				
				for(i=0;i<list->numitems;i++)
				{
					DisplayPathName(EVERYTHING_IPC_ITEMPATH(list,&list->items[i]),EVERYTHING_IPC_ITEMFILENAME(list,&list->items[i]))
				}
				
				return TRUE;
			}
			
			break;
		}
	}
	
	return DefWindowProc(hwnd,msg,wParam,lParam);
}