Stringstreams in File I/O

[alpha8]

I really don't understand how to write this program using string streams. Can someone please guide me in the right direction?

Your input file will include census data. A line of the file will either describe a family, or be effectively blank; either kind of line may have a comment appended, where a comment starts with // and continues to the end of the line. A line that describes a family will have the family’s yearly income (preceded by a $) and the number of members. The income may be represented as a double; the number of members could be either represented as an int or an unsigned. The income must be in [0, 1000000], and the number of members must be in [1, 10].

Examples of legal input lines (including the blank line immediately following this line):

$50000.00 1
$0 10 // blah blah blah
// Now is the time for all good men
$1000000 10 // decimal point in income field is optional

Examples of illegal input lines are
50000.00 1
%50000.00 1
$blah 1
$-5 1
$1000001 1
$50000
$50000 blah
$50000 0
$50000 11
$50000 1 1
$50000 1.0
$50000 1 blah

You program is supposed to read from the input file and write to the output file. If it ever encounters an illegal input line, c&d. None of the comments in the input file are transferred to the output file.
For each family described in the input file, the output file is supposed to have a line giving the average income per family member, preceded by $.

For example, if the input file consisted of the 5 legal lines I gave above, then your output file should have the following 3 lines:
$50000
$0
$100000
As you see, the third line gives $1000000 / 10, which is $100000.

[MiiNiPaa]

1) Get line from a file
2) Remove comments
3) create a string stream from your line
4) Read a character, double and int.
5) Confirm ranges of your variables , that a character is '&' and there is no non-whitespace characters in a line
6) output if needed.
7) repeat