I think your problem is not the script but even before. Let us talk about the program structure prior to attempting to solve it in any language.

1. You need some kind of input validation. How should your program react when the input is unintelligible? Throw an error? Try to correct it? Leave it to the user to recognize that some output might be nonsense? Have correct input as a (silent) prerequisite?

Every answer to this is "valid" in its own right, but you will have to answer it before you can even try to create some program logic. Programming is automated problem solving - you could, using your file, convert currencies yourself (otherwise you wouldn't be able to write program at all). The program is just a generalized, fomalized description of what you would do.

It is good style to document with every possible exactitude what *is* done by the program and what *isn't*. Doing "A and B, but not C and D" is absolutely ok, but stopping for no obvious reason is not. Leaving it to the user to find out when the program output is valid and when it is non-sensical is not ok either.

2) Create a program logic before creating code. This helps in bringing your thoughts to formal conclusion. There are some formal approaches to this, but every method is as good as any other - what really helps is that you do it at all.

You probably have seen people - programmers - hearing a problem description and start right away typing code. They do in fact the same - create some plan first - but they are that much trained that they can do it in mind and instantly. Very likely they go back to coming up with such a "program plan" first before writing the code once the problem gets complex enough.

Write your plan here, we will discuss it and only then implement it.

I hope this helps.

bakunin