I think the unfamaliarity would be addressed by reading it up, and
trying to understand it. If you define an addrescode field as 'char'
would you expect Oracle strips the leading zeroes?
Also what you propose above is simply not possible: if you manage to
concatenate individual columns together, there is nothing that can
parse it, as such parsing will never be fool proof.

--
Sybrand Bakker, Senior Oracle DBA

Well, it isn't a csv (comma separated value) file, since it is
separated by semicolons, but that really doesn't matter.  You can trim
the zeroes from in front of the addrcode, but why not make a number
column instead?  I have been in the same situation, where you don't
have control of the structure that the data comes from or goes into and
you have to parse an address column and load the data into separate
fields in a new table.  Although nothing is foolproof, most conversions
are better than not converting it, or losing the data.  I like to use
functions to extract and validate.  You can use such functions directly
in SQL*Loader, but I don't think you can use them directly in external
tables.  However, you can load your data into a staging table, then
insert it into your other table using the functions.  Please see the
demonstration below, which shows how to do it either using SQL*Loader
or an external table and an insert.  The functions were created to your
specifications, but you may want to test, check your data, and see if
you need to make revisions.

-- functions:
scott@ORA92> CREATE OR REPLACE FUNCTION extract_streetname
 2    (p_streetname IN VARCHAR2)
 3    RETURN VARCHAR2
 4  AS
 5    v_int        INTEGER := 6;
 6  BEGIN
 7    WHILE SUBSTR (p_streetname, v_int, 1)
 8      NOT IN ('1', '2', '3', '4', '5', '6', '7', '8', '9')
 9    LOOP
10      v_int := v_int + 1;
11    END LOOP;
12    RETURN SUBSTR (p_streetname, 1, v_int - 1);
13  EXCEPTION
14    WHEN OTHERS THEN
15      RETURN p_streetname;
16  END extract_streetname;
17  /

Function created.

scott@ORA92> SHOW ERRORS
No errors.
scott@ORA92> CREATE OR REPLACE FUNCTION extract_streetno
 2    (p_streetname IN VARCHAR2)
 3    RETURN VARCHAR2
 4  AS
 5    v_streetno    VARCHAR2(25) := SUBSTR (p_streetname, 6);
 6  BEGIN
 7    WHILE SUBSTR (v_streetno, 1, 1) NOT IN
 8      ('1', '2', '3', '4', '5', '6', '7', '8', '9')
 9    LOOP
10      v_streetno := SUBSTR (v_streetno, 2);
11    END LOOP;
12    RETURN v_streetno;
13  EXCEPTION
14    WHEN OTHERS THEN
15      RETURN NULL;
16  END extract_streetno;
17  /

Function created.

scott@ORA92> SHOW ERRORS
No errors.
scott@ORA92> CREATE OR REPLACE FUNCTION my_to_date
 2    (p_date IN VARCHAR2)
 3    RETURN DATE
 4  AS
 5  BEGIN
 6    RETURN TO_DATE (p_date, 'DDMMYYYY');
 7  EXCEPTION
 8    WHEN OTHERS THEN
 9      RETURN NULL;
10  END my_to_date;
11  /

Function created.

scott@ORA92> SHOW ERRORS
No errors.

-- table:
scott@ORA92> CREATE TABLE addr_ext
 2    (addrcode   VARCHAR2(10),
 3      streetname VARCHAR2(25),
 4      streetno   VARCHAR2(25),
 5      addrdate   DATE)
 6  /

Table created.

-- SQL*Loader control file and load:
LOAD DATA
INFILE 'c:\ext_tables\addr.csv'
INTO TABLE addr_ext
FIELDS TERMINATED BY ';'
TRAILING NULLCOLS
(addrcode   "LTRIM (:addrcode, '0')",
streetname "extract_streetname (:streetname)",
addrdate   "my_to_date (:addrdate)",
streetno   "extract_streetno (:streetname)")

scott@ORA92>-HOST SQLLDR scott/tiger CONTROL=addr.ctl LOG=addr.log

-- or external table and insert:
scott@ORA92> CREATE OR REPLACE DIRECTORY ext_tables AS 'c:\ext_tables'
 2  /

Directory created.

scott@ORA92> CREATE TABLE addr_ext_load
 2    (addrcode   VARCHAR2(10),
 3      streetname VARCHAR2(25),
 4      addrdate   VARCHAR2(8))
 5  ORGANIZATION external
 6    (TYPE ORACLE_LOADER
 7      DEFAULT DIRECTORY ext_tables
 8      ACCESS PARAMETERS
 9       (RECORDS DELIMITED BY NEWLINE
10        FIELDS TERMINATED BY ";"
11        MISSING FIELD VALUES ARE NULL
12          (addrcode    CHAR,
13           streetname CHAR,
14           addrdate    CHAR))
15      LOCATION ('addr.csv'))
16  REJECT LIMIT UNLIMITED
17  /

Table created.

scott@ORA92> INSERT INTO addr_ext (addrcode, streetname, streetno,
addrdate)
 2  SELECT LTRIM (addrcode, '0'),
 3         extract_streetname (streetname),
 4         extract_streetno (streetname),
 5         my_to_date (addrdate)
 6  FROM   addr_ext_load
 7  /

3 rows created.

-- results either way:
scott@ORA92> SELECT * FROM addr_ext
 2  /

ADDRCODE   STREETNAME                STREETNO                  ADDRDATE
---------- ------------------------- -------------------------
---------
101        Fox Street                20 A
27-MAY-05
102        42nd Street               20921
25-FEB-05
105        Fox Street                21

scott@ORA92>

[snip]

If you take Sybrand' advice and use a little of your own
imagination, then you might come up with something like this:

create or replace function GetAddrCode( addrcode in varchar2 )
return varchar2 as
begin
  return to_char( to_number( addrcode ) );
EXCEPTION
  when others then
  return null;
end GetAddrCode;
/

You could of course have performed the coersion in place, but
having a function allows you to write neater code in larger
contexts, ime and imo.

Hope this help's.

Cheers,
Chris Val