In order to expedite an answer to your question, please provide as much of the following information as possible
- What programming language/platform or application are you using?
- What is your ultimate task? What are you working on and what you want to use a Regular Expression for in your planned solution.
- Describe your Regular Expressions-related problem with the task and
what you have attempted so far. Please be fairly descriptive.
- If possible and if it is not an extremely large block of text,
please provide a representative example of the original text you are
trying to process.Do not make up a sample. Do not oversimplify
complexity of your real data. Also show what your desired result
should look like. If you can not provide a sampling of your real data,
describe it as thoroughly as you can.
Thank You

An Example of a Poorly asked Question:
I need regex to match only characters and numbers.
Why is this a poor question:
- Vague question: characters are anything that can be used in a print
format. Not only do they include numbers, but thousands of other things
as well.
- No sample text was provided. A sample of text you are working with
may allow for your otherwise vague question's scope be determined. Plus
it gives the regex writer something to verify/test an offered solution.
And it may give your problem some needed context.
- The programming environment was not mentioned. What good does an
offered solution do if it features an option not supported by your
language or application?
- No high-level overview of the problem/task was given. As great as
regexes are they can't do everything. Sometimes there are better,
simpler solutions not involving regexes. Some problems can't be solved
by regexes.

Better question:
I need a regex that matches a string containing only the letters of the
english alphabet, upper and lower case, and digits. I'm trying to
_________. I'm working with/in ___________. For this input __________
these values should match ___, ____, ___, These values should not ___,
____, ___.
Michael
"In theory, theory and practice are the same. In practice, they are not."
Albert Einstein