Solved

Regular Expressions

Posted on 2008-10-18
5
258 Views
Last Modified: 2013-11-23
hello experts,

i've been given the following regular expression "\\.\\d+|\\d+(?:\\.\\d+)?|[+-/*()%^]|\\w{3,4}|[a-zA-Z]" and im having a little trouble decoding it.

from my understanding of RE's (which isnt very much), this expression is split up into four types/categories. "[+-/*()%^]" being the normal chars, "\\w{3,4}" i would think are words of 3 or 4 letters, "[a-zA-Z]" being a letter of the alphabet, however i have absolutely no idea what the first two categories ("\\.\\d+|\\d+(?:\\.\\d+)?") represent. im guessing it has to do with numerical float values, but other then that no clue.

anyone have any idea?

cheers
0
Comment
Question by:gem56
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
5 Comments
 
LVL 11

Expert Comment

by:miqrogroove
ID: 22751216
\\.\\d+
This is a literal period, followed by one or more digits.

\\d+(?:\\.\\d+)?
This one I'm a bit confused about myself.  If I can give you a solid intrepretation I will follow up.
0
 
LVL 11

Accepted Solution

by:
miqrogroove earned 125 total points
ID: 22751224
\\d+(?:\\.\\d+)?
One or more digits followed optionally by: a literal period and one or more digits.

The syntax (?:) creates a non-backreferenced grouping, which is done only for speed optimization.

Enjoy!
0
 

Author Comment

by:gem56
ID: 22751228
thanks mate.

by the looks of it "\\d+(?:\\.\\d+)?" will probably translate to <digit>.<more digits> so looks like its just a formatting thing so it matches both "0.45" and ".45". any chance you could confirm?

cheers
0
 
LVL 11

Expert Comment

by:miqrogroove
ID: 22751235
See my second message ;)

"\\d+(?:\\.\\d+)?" will match "0.45" and not ".45"
0
 

Author Comment

by:gem56
ID: 22751302
yep, beat me to the post :P

thanks champ

0

Featured Post

PeopleSoft Has Never Been Easier

PeopleSoft Adoption Made Smooth & Simple!

On-The-Job Training Is made Intuitive & Easy With WalkMe's On-Screen Guidance Tool.  Claim Your Free WalkMe Account Now

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

INTRODUCTION Working with files is a moderately common task in Java.  For most projects hard coding the file names, using parameters in configuration files, or using command-line arguments is sufficient.   However, when your application has vi…
Introduction This article is the first of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article explains our test automation goals. Then rationale is given for the tools we use to a…
Video by: Michael
Viewers learn about how to reduce the potential repetitiveness of coding in main by developing methods to perform specific tasks for their program. Additionally, objects are introduced for the purpose of learning how to call methods in Java. Define …
Viewers will learn about if statements in Java and their use The if statement: The condition required to create an if statement: Variations of if statements: An example using if statements:
Suggested Courses

624 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question