Memcached::getResultCode

00 = MEMCACHED_SUCCESS01 = MEMCACHED_FAILURE02 = MEMCACHED_HOST_LOOKUP_FAILURE // getaddrinfo() and getnameinfo() only03 = MEMCACHED_CONNECTION_FAILURE04 = MEMCACHED_CONNECTION_BIND_FAILURE // DEPRECATED see MEMCACHED_HOST_LOOKUP_FAILURE05 = MEMCACHED_WRITE_FAILURE06 = MEMCACHED_READ_FAILURE07 = MEMCACHED_UNKNOWN_READ_FAILURE08 = MEMCACHED_PROTOCOL_ERROR09 = MEMCACHED_CLIENT_ERROR10 = MEMCACHED_SERVER_ERROR // Server returns "SERVER_ERROR"11 = MEMCACHED_ERROR // Server returns "ERROR"12 = MEMCACHED_DATA_EXISTS13 = MEMCACHED_DATA_DOES_NOT_EXIST14 = MEMCACHED_NOTSTORED15 = MEMCACHED_STORED16 = MEMCACHED_NOTFOUND17 = MEMCACHED_MEMORY_ALLOCATION_FAILURE18 = MEMCACHED_PARTIAL_READ19 = MEMCACHED_SOME_ERRORS20 = MEMCACHED_NO_SERVERS21 = MEMCACHED_END22 = MEMCACHED_DELETED23 = MEMCACHED_VALUE24 = MEMCACHED_STAT25 = MEMCACHED_ITEM26 = MEMCACHED_ERRNO27 = MEMCACHED_FAIL_UNIX_SOCKET // DEPRECATED28 = MEMCACHED_NOT_SUPPORTED29 = MEMCACHED_NO_KEY_PROVIDED /* Deprecated. Use MEMCACHED_BAD_KEY_PROVIDED! */30 = MEMCACHED_FETCH_NOTFINISHED31 = MEMCACHED_TIMEOUT32 = MEMCACHED_BUFFERED33 = MEMCACHED_BAD_KEY_PROVIDED34 = MEMCACHED_INVALID_HOST_PROTOCOL35 = MEMCACHED_SERVER_MARKED_DEAD36 = MEMCACHED_UNKNOWN_STAT_KEY37 = MEMCACHED_E2BIG38 = MEMCACHED_INVALID_ARGUMENTS39 = MEMCACHED_KEY_TOO_BIG40 = MEMCACHED_AUTH_PROBLEM41 = MEMCACHED_AUTH_FAILURE42 = MEMCACHED_AUTH_CONTINUE43 = MEMCACHED_PARSE_ERROR44 = MEMCACHED_PARSE_USER_ERROR45 = MEMCACHED_DEPRECATED46 = MEMCACHED_IN_PROGRESS47 = MEMCACHED_SERVER_TEMPORARILY_DISABLED48 = MEMCACHED_SERVER_MEMORY_ALLOCATION_FAILURE49 = MEMCACHED_MAXIMUM_RETURN /* Always add new error code before */11 = MEMCACHED_CONNECTION_SOCKET_CREATE_FAILURE = MEMCACHED_ERROR

A more up to date and correct list of the result codes (Note that ERR_NO maps to 26 not 25 as stated above):Memcached::OPT_COMPRESSION - -1001Memcached::OPT_SERIALIZER - -1003Memcached::SERIALIZER_PHP - 1Memcached::SERIALIZER_IGBINARY - 2Memcached::SERIALIZER_JSON - 3Memcached::OPT_PREFIX_KEY - -1002Memcached::OPT_HASH - 2Memcached::HASH_DEFAULT - 0Memcached::HASH_MD5 - 1Memcached::HASH_CRC - 2Memcached::HASH_FNV1_64 - 3Memcached::HASH_FNV1A_64 - 4Memcached::HASH_FNV1_32 - 5Memcached::HASH_FNV1A_32 - 6Memcached::HASH_HSIEH - 7Memcached::HASH_MURMUR - 8Memcached::OPT_DISTRIBUTION - 9Memcached::DISTRIBUTION_MODULA - 0Memcached::DISTRIBUTION_CONSISTENT - 1Memcached::OPT_LIBKETAMA_COMPATIBLE - 16Memcached::OPT_BUFFER_WRITES - 10Memcached::OPT_BINARY_PROTOCOL - 18Memcached::OPT_NO_BLOCK - 0Memcached::OPT_TCP_NODELAY - 1Memcached::OPT_SOCKET_SEND_SIZE - 4Memcached::OPT_SOCKET_RECV_SIZE - 5Memcached::OPT_CONNECT_TIMEOUT - 14Memcached::OPT_RETRY_TIMEOUT - 15Memcached::OPT_SEND_TIMEOUT - 19Memcached::OPT_RECV_TIMEOUT - 15Memcached::OPT_POLL_TIMEOUT - 8Memcached::OPT_CACHE_LOOKUPS - 6Memcached::OPT_SERVER_FAILURE_LIMIT - 21Memcached::HAVE_IGBINARY - #&UNDEFINED;#Memcached::HAVE_JSON - #&UNDEFINED;#Memcached::GET_PRESERVE_ORDER - 1Memcached::RES_SUCCESS - 0Memcached::RES_FAILURE - 1Memcached::RES_HOST_LOOKUP_FAILURE - 2Memcached::RES_UNKNOWN_READ_FAILURE - 7Memcached::RES_PROTOCOL_ERROR - 8Memcached::RES_CLIENT_ERROR - 9Memcached::RES_SERVER_ERROR - 10Memcached::RES_WRITE_FAILURE - 5Memcached::RES_DATA_EXISTS - 12Memcached::RES_NOTSTORED - 14Memcached::RES_NOTFOUND - 16Memcached::RES_PARTIAL_READ - 18Memcached::RES_SOME_ERRORS - 19Memcached::RES_NO_SERVERS - 20Memcached::RES_END - 21Memcached::RES_ERRNO - 26Memcached::RES_BUFFERED - 32Memcached::RES_TIMEOUT - 31Memcached::RES_BAD_KEY_PROVIDED - 33Memcached::RES_CONNECTION_SOCKET_CREATE_FAILURE - 11Memcached::RES_PAYLOAD_FAILURE - -1001