Please enter your pattern (as a regular expression) and data; this program will show below if the data matches the pattern. You can select a common pattern to get started.
Some key parts of the regex language:
When using regular expressions as a filter, be sure that it begins with ^ (match data beginning) and ends with $ (match data ending). Beware: the | has lower precedence.
Regexper.com provides a delightful visualization of regular expressions.
You can get a similar text-based C program regex.c if you want to try out POSIX EREs instead of Javascript regular expressions (they have much in common but are not identical).
(C) Copyright 2012 David A. Wheeler.