Case 1

/* Eventfilter */
UA_EventFilter filter;
UA_EventFilter_init(&filter);

/* query string */
char *inp = "SELECT\n"
            "\n"
            "PATH \"/Message\",\n"
            "PATH \"/Severity\",\n"
            "PATH \"/EventType\"\n"
            "\n"
            "WHERE\n"
            "OFTYPE ns=1;i=5001";

/* UA_EventFilter_parse takes a Bytestring as input*/
UA_ByteString case_1 = UA_String_fromChars(inp);
/* create the eventfilter from the string */
UA_EventFilter_parse(filter, &case_1);

UA_ByteString_clear(&case_1);

The generated Eventfilter looks likes this:

{
    SelectClauses: [
            {
                    TypeDefinitionId: "i=2041",
                    BrowsePath: [
                            {
                                    Name: "Message"
                            }
                    ],
                    AttributeId: 13,
                    IndexRange: null
            },
            {
                    TypeDefinitionId: "i=2041",
                    BrowsePath: [
                            {
                                    Name: "Severity"
                            }
                    ],
                    AttributeId: 13,
                    IndexRange: null
            },
            {
                    TypeDefinitionId: "i=2041",
                    BrowsePath: [
                            {
                                    Name: "EventType"
                            }
                    ],
                    AttributeId: 13,
                    IndexRange: null
            }
    ],
    WhereClause: {
            Elements: [
                    {
                            FilterOperator: 14,
                            FilterOperands: [
                                    {
                                            TypeId: "i=595",
                                            Body: {
                                                    Value: {
                                                            Type: NodeId,
                                                            Body: "ns=1;i=5001"
                                                    }
                                            }
                                    }
                            ]
                    }
            ]
    }
}