how to change IP:client_addr to be a digital value

Does anybody know how to convert IP:client_addr string to be digital value. And also , how to convert digital value to be IP_addr string.

 

I just need to SNAT 10.0.0.0/8 to 200.1.1.0/24, but I need to keep one client using one snat addr ,not random pickup the snataddr, something like hash the client addr to a snatpool.