Static analysis says:
src\zmq.cpp(489): error V220: Suspicious sequence of types castings: memsize -> 32-bit integer -> memsize. The value being casted: '* count_'.
src\zmq.cpp(510): error V127: An overflow of the 32-bit 'nread' variable is possible inside a long cycle which utilizes a memsize-type loop counter.

I've silenced the warning on line 489 and ignored the other.
But also, it looks to me like there's a serious bug here: The
out-parameter "count_" is never set to zero before we start
incrementing it. So its final value will always be between
1 and 2 times its initial value. The fix seems obvious.