Parsing And Getting Specific Values From CSV String?

I am having a string in CSV format.http:[code].....I can add new values to it by some mechanism. Everything will be same except the new values will have numeric part = 0. Take example I have this exsiting CSV string

1 , abc.txt , 2 , def.doc , 3 , flyaway.txt

Now by some mechanism i added two more files Superman.txt and Spiderman.txt to the existing string. Now it became

1 , abc.txt , 2 , def.doc , 3 , flyaway.txt, 0, Superman.txt, 0 , Spiderman.txt

What i am doing here is that this csv string is paased into SP where its splitted and inserted to db. So for inserting I have to take the files with numeric part 0 only rest will be omiited .Which will be further then converted into CSV string.Array will look like this

str[0]="1"
str[1]="abc.txt"
str[2]="2"[code].....

So at last i want to say my input will be

1 , abc.txt , 2 , def.doc , 3 , flyaway.txt, 0, Superman.txt, 0 , Spiderman.txt

Desired Output:

0, Superman.txt, 0 , Spiderman.txt