How to handle comma in a comma delimited file?

CASE 1: More than one Comma [,] is appearing just after delimiter [,]
CASE 2: Comma is [,] appearing in a data itself. Ex: Address column has data like this 'CA,USA'
CASE 3: Any other Char like [+] Char is appearing anywhere in data. [,]

Practically
CASE 1: More than one Comma [,] is appearing just after delimiter [,]
Data
CID,  CNAME, CITY, CNTRY,  PHONE NUMBER
1234,,,SMITH,CA,USA,,,9845679000
1235,JOHN,NY,USA,9996805944
1236,NORMA,,,CA,USA,,,7804567893
1237,CARL,,,NY,USA,889950493
Solution: It's very easy to handle. Informatica has already provided an option to handle this case.

While Importing File metadata of source file in Flat File Import wizard Step 2 of 3 Check Treat consecutive delimiter as one 

Now, it's good to go ahead with source file.
CASE 2: Comma is [,] appearing in a data itself. Ex: Address column has data like this 'CA,USA'
Data
CID, CNAME, ADD, PHONE_NUMBER
1234,SMITH,CA,USA,9845679000
1235,JOHN,NY,USA,9996805944
1236,NORMA,CA,USA,7804567893
1237,CARL,NY,USA,8899504934

Solution: There are two approach to resolve this issue.
Approach 1: Through Script modify your source and put Single Quotes or Double Quotes for each and every value.
Data After Modification
CID, CNAME, ADD, PHONE_NUMBER
'1234','SMITH','CA,USA','9845679000'
'1235','JOHN','NY,USA','9996805944'
'1236','NORMA','CA,USA','7804567893'
'1237','CARL','NY,USA','8899504934'
While Importing File metadata of in Flat File Import wizard Step 2 of 3 select Radio Button of Text Qualifier section Single Quotes. (If you have modified your source with double quotes then please select double quotes)

Approach 2: Read complete file as fixed width and in the expression with the help of SUBSTR() and INSTR() function split into columns. Only one thing we need to take care while splitting third column data we have to start from second occurrence of comma till fouth occurrence of comma.
(In many other scenarios we have already completed this.)
A real time Secret :-) We are creating Reusable transformation for splitting records into column based upon delimited char and we are using that whenever we need.
A second case where we are dependent upon reusable transformation is for removing unwanted space from data while reading from files. Yes,  LTRM(RTRIM())
CASE 3: Any other Char like [+] Char is appearing anywhere in data. [,]
CID, CNAME, ADD, PHONE_NUMBER
1234,SMITH,CA,USA,+19845679000
1235,JOHN,NY,USA,+19996805944
1236,NORMA,CA,USA,+17804567893
1237,CARL,NY,USA,+18899504934
Solution: While Importing File metadata of in Flat File Import wizard Step 2 of 3 Check Remove escape character from data and give you Char + in Text Box.

Thanks

Ur's Hari