(PHP 4 >= 4.3.3, PHP 5)
snmp_get_valueretrieval — Return the method how the SNMP values will be returned
   OR-ed combitantion of constants ( SNMP_VALUE_LIBRARY or
   SNMP_VALUE_PLAIN ) with
   possible SNMP_VALUE_OBJECT set.
  
Example #1 Using snmp_get_valueretrieval
<?php
 $ret = snmpget('localhost', 'public', 'IF-MIB::ifName.1');
 if (snmp_get_valueretrieval() & SNMP_VALUE_OBJECT) {
   echo $ret->value;
 } else {
   echo $ret;
 }
?>