Number of fields in split()

Hello-
I'm running postgres 8.0.8 on Gento Linux and have a text field
delimited with tildes that I am splitting using split_part(). Is there
a way to tell how many "parts" I have? For example:

1~22~33 would split into 3 fields
1~2~3~4 would split into 4 fields

In Python I would do:

fields = '1~22~333'.split('~')

and then len(fields) would be 3, so I would know there were 3 fields to
process.

Another way to solve this problem would be to determine the names of
columns in a given table. Is there a way to get that information?

I want this information so I can build insert and update queries on the
fly in my pgplsql functions.

Thanks for your help,
--greg