C.mpz_export(unsafe.Pointer(&b[0]), &n, 1, 1, 1, 0, &z.i[0])
	return b[0:n]
}

// Len returns the length of z in bits.  0 is considered to have length 1.
func (z *Int) Len() int {
	z.doinit()
	return int(C.mpz_sizeinbase(&z.i[0], 2))
}

// Set sets z = x and returns z.
func (z *Int) Set(x *Int) *Int {
	z.doinit()
	C.mpz_set(&z.i[0], &x.i[0])
	return z
}