Question

Suppose a user selects a file in a dialogue box, and the app then opens the file for reading, etc. Users can open “incorrect” files–they can select a binary file, for example, even if the file they’re supposed to be selecting is a text file.

I recognize that sometimes improper file types generate exceptions, which can be handled. But sometimes the files don’t create exceptions; instead, they just cause the application to work improperly.

What’s the standard way to code for these kinds of situations?

Answer 1

1. Put a unique identifier into the file (usually the first line or some tag)
2. Restrict the file extension
3. Do a check on the file whether it’s OK

Use 1. if possible or use both 2. and 3.