[Libvir] Need Help on Error handling.

Hi, I am using libvirt to manage, The Hypervisor, Can Any one Help me about handling error? My main questions are. --- What is Library level Error Handling? --- Any Example to use void virSetErrorFunc (void * userData,virErrorFunc <http://libvirt.org/html/libvirt-virterror.html#virErrorFunc> handler) --- What is the difference between these two funtions? int virConnCopyLastError (virConnectPtr <http://libvirt.org/html/libvirt-libvirt.html#virConnectPtr> conn,virErrorPtr <http://libvirt.org/html/libvirt-virterror.html#virErrorPtr> to) virErrorPtr <http://libvirt.org/html/libvirt-virterror.html#virErrorPtr> virConnGetLastError (virConnectPtr <http://libvirt.org/html/libvirt-libvirt.html#virConnectPtr> conn) -- Thanks&Regards Ajeesh