Validate Email by regular Expression... Need Help

Question

Dear All,
Requirement:
validate the email ID entered & throw error message, if it is invalid.
DATA c_mailpattern TYPE c LENGTH 60 VALUE
'[a-zA-Z0-9._%-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4} '.
** If @ is present, more than once. Error out
    find ALL OCCURRENCES OF '@' in P_email
    MATCH COUNT v_count.
    if v_count > 1.
      v_badpattern = 1.
    endif.
** If , is present, once, Error out
    find ALL OCCURRENCES OF ',' in P_Email
    MATCH COUNT v_count.
    if v_count > 0.
      v_badpattern = v_badpattern + 1.
    endif.
    FIND REGEX c_mailpattern IN P_Email IGNORING CASE .
    IF sy-subrc <> 0 OR v_badpattern > 0.
Write:/ p_EMAIL, 'has invalid Email format'.
ENDIF.
though this works fine, tester needs me to catch, if domain name has "app.com.com"  as invalid email id.
above regex fails in such case.
I searched & found
{messageID=3706355}
messageID=1657369}{
https://wiki.sdn.sap.com/wiki/display/Snippets/E-MAIL+Validation
doesn't help.
I found this regex in a perl program.
[a-z0-9!#$%&'{size:14}*+{size:14}/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?
Can I get help to modify this  into ABAP String?
1) I can't bypass the boldened text using Escape characters like #* or '' Can some one help me assign this regex-string into a string variable?
2) This regex is longer than allowed length for a literal.
It can be split into 2 strings, then concatenated & checked.
Edited by: Mallikarjuna J on May 16, 2011 8:23 PM
Edited by: Mallikarjuna J on May 16, 2011 8:26 PM

Answer 1

Thanks Sebastian, Pratik & Keshav for the replies.
SX_INTERNET_ADDRESS_TO_NORMAL doesn't validate a wrong email ID. It only splits the internet address into mail & domain.
Prathik,
just .com.com is not the point, Bad input could be .net.ent or .net.com or so....
Amol, Thanks, but I keep receiving Error, not found in the 41 line response I get
I think we need to check not line 2 but line 28.
Taking cue from Prathik, I'm planning to put this
*** ls_inputmail-mail is the email-id entered by user.
************ Check for Valid Regular Expression
*****   DOT(.) is allowed more than once,
*****   @ is allowed only once,
*****   , is not allowed.
** If @ is present, more than once. Error out
    find ALL OCCURRENCES OF '@' in ls_input_mail-mail
    MATCH COUNT v_count.
    if v_count > 1.
      v_badpattern = 1.
    endif.
** If , is present, once, Error out
    find ALL OCCURRENCES OF ',' in ls_input_mail-mail
    MATCH COUNT v_count.
    if v_count > 0.
      v_badpattern = v_badpattern + 1.
    endif.
**   Find if domain part i.e., after @ has errors.
    SPLIT ls_input_mail-mail at '@' into v_mailpart v_domain.
*    there's a dot in the domain.
    if v_domain Co '.' .
*     last 2 char can only be country name, not anything else.
      SPLIT v_domain at '@' into v_domain1 v_domain2.
*      v_domain2 can only be a country name, else error out
  select single landx from t005 into v_country
    where landx = v_domain2.
    if sy-subrc <> 0.
      v_badpattern = v_badpattern + 1.
    endif. 
    ENDIF. 
    FIND REGEX c_mailpattern IN ls_input_mail-mail IGNORING CASE .
    IF sy-subrc <> 0 OR v_badpattern > 0.
Write:/ ls_inputmail-mail, 'has invalid email format'.
  ENDIF.
However, I was wondering, if there was a way to  use escapae characters & make the beow string as a valid regex variable to check email id.
[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?
Nevertheless, Thanks Friends for all your inputs.
Edited by: Mallikarjuna J on May 17, 2011 2:23 PM