How to open a file, read from it, and retrieve information from it?

[Bugsyboy9]

>From a GUI interface, a user needs to request a string to be searched
from a file and bring the string back, if it is in the file, and
display it in a different field within the same GUI.  Basically, I
need to be able to open a file, parse its contents, and bring the
requested information back and display it in a GUI window.

Any assistance would be appreciated.


Thanks.