(PHP 5 >= 5.2.0)
snmp_set_oid_output_format — Set the OID output format
$oid_format = SNMP_OID_OUTPUT_MODULE
   )snmp_set_oid_output_format() sets the output format to be full or numeric.
oid_format| SNMP_OID_OUTPUT_FULL | .iso.org.dod.internet.mgmt.mib-2.system.sysUpTime.sysUpTimeInstance | 
| SNMP_OID_OUTPUT_NUMERIC | .1.3.6.1.2.1.1.3.0 | 
Begining from PHP 5.4.0 four additional constants available:
| SNMP_OID_OUTPUT_MODULE | DISMAN-EVENT-MIB::sysUpTimeInstance | 
| SNMP_OID_OUTPUT_SUFFIX | sysUpTimeInstance | 
| SNMP_OID_OUTPUT_UCD | system.sysUpTime.sysUpTimeInstance | 
| SNMP_OID_OUTPUT_NONE | Undefined | 
No value is returned.
Note:
snmp_set_oid_output_format() is only available when using the UCD SNMP library. This function is not available when using the Windows SNMP library.
Example #1 Using snmprealwalk()
<?php
 snmp_read_mib("/usr/share/mibs/netsnmp/NET-SNMP-TC");
 // default or SNMP_OID_OUTPUT_MODULE in PHP >= 5.3.6
 print_r( snmprealwalk('localhost', 'public', 'RFC1213-MIB::sysObjectID') );
 snmp_set_oid_output_format(SNMP_OID_OUTPUT_NUMERIC);
 print_r( snmprealwalk('localhost', 'public', 'RFC1213-MIB::sysObjectID') );
 snmp_set_oid_output_format(SNMP_OID_OUTPUT_FULL);
 print_r( snmprealwalk('localhost', 'public', 'RFC1213-MIB::sysObjectID') );
?>
The above would output:
 Array
 (
    [RFC1213-MIB::sysObjectID.0] => OID: NET-SNMP-TC::linux
 )
 Array
 (
    [.1.3.6.1.2.1.1.2.0] => OID: .1.3.6.1.4.1.8072.3.2.10
 )
 Array
 (
    [.iso.org.dod.internet.mgmt.mib-2.system.sysObjectID.0] => OID: .iso.org.dod.internet.private.enterprises.netSnmp.netSnmpEnumerations.netSnmpAgentOIDs.linux
 )