Trent Mick <trentm@activestate.com>: The common technique for printing out a pointer has been to cast to a long and use the "%lx" printf modifier. This is incorrect on Win64 where casting to a long truncates the pointer. The "%p" formatter should be used instead. The problem as stated by Tim: > Unfortunately, the C committee refused to define what %p conversion "looks > like" -- they explicitly allowed it to be implementation-defined. Older > versions of Microsoft C even stuck a colon in the middle of the address (in > the days of segment+offset addressing)! The result is that the hex value of a pointer will maybe/maybe not have a 0x prepended to it. Notes on the patch: There are two main classes of changes: - in the various repr() functions that print out pointers - debugging printf's in the various thread_*.h files (these are why the patch is large) Closes SourceForge patch #100505.

--- a/Objects/bufferobject.c	Fri Jun 30 14:58:20 2000 +0000
+++ b/Objects/bufferobject.c	Fri Jun 30 15:01:00 2000 +0000
@@ -241,20 +241,20 @@
 
 	if ( self->b_base == NULL )
 	{
-		sprintf(buf, "<%s buffer ptr %lx, size %d at %lx>",
+		sprintf(buf, "<%s buffer ptr %p, size %d at %p>",
 			status,
-			(long)self->b_ptr,
+			self->b_ptr,
 			self->b_size,
-			(long)self);
+			self);
 	}
 	else
 	{
-		sprintf(buf, "<%s buffer for %lx, ptr %lx, size %d at %lx>",
+		sprintf(buf, "<%s buffer for %p, ptr %p, size %d at %p>",
 			status,
-			(long)self->b_base,
-			(long)self->b_ptr,
+			self->b_base,
+			self->b_ptr,
 			self->b_size,
-			(long)self);
+			self);
 	}
 
 	return PyString_FromString(buf);