Retrieve data using SNMP

[harshanahnd]

I developed an snmp application which can retrieve data from a router (referring to a code given in http://www.java2s.com/Code/CSharp/Network/SimpleSNMP.htm )

I was able to retrieve information such as router name(string), number of interfaces in has (integer). I extracted this information from the packet received by the router. There are some more information that I want to get from the router like its interface data(ifSpeed, ifInOctets, ifOutOctets described in RFC1213 www.freesoft.org/CIE/RFC/1213/23.htm)
I can send a packet requesting these data but dont know how to extract relevant data from the packet.
What I dont know here is if I request for ifSpeed the return packet has a value type "GAUGE", How to get the integer value from this?? Similarly ifInOctets returning the type "COUNTER"

Thanks for your valuable time.