""Murray @ PlanetThoughtful"" <lists@xxxxxxxxxxxxxxxxxxxx> wrote in message news:7A.95.23233.1F00F134@xxxxxxxxxxxxxxx > > Hi all, > > > > > > I want to write regular expression for checking the string format entered > > by user. > > > > the allowed formats are > > > > examples: > > 10 > > 10, > > 10,12-10 > > 12-10 > > > > that is the valid strings are: > > 1. only integer > > 2. an integer, range of integers example 3 > > > > and no other characters must be allowed. You could simplify the matter by replacing all "-" and "," with, say, 0 and then using the simple "\d+" (I think) regexp. > > Hi babu, > > As you've pointed out, you have 4 distinct scenarios to deal with, and it > may be very difficult, without a great deal of tuning and tweaking, to > define a regular expression that can effectively match all 4 scenarios > without including false matches as well. > > One way of dealing with this is to build more specialized and exact regular > expressions for each possible scenario and group them together in an if > statement. > > Eg. > > if (preg_match('/^\d+$/',$subject) || preg_match('/^\d+,$/',$subject) || > preg_match('/^\d+,\d+-\d+$/', $subject) || <etc etc>){ > > // code for successful match of valid data in $subject > > } else { > > // code for invalid data in $subject > > } > > Basically, the if/else statement is testing each distinct possible pattern > and executing code if any of those distinct possible patterns match. > > It may not ultimately be the most graceful way of dealing with the > situation, but having spent many hours attempting to tweak complex regular > expressions looking for the magic combination, I've learned that breaking > scenarios down this way can save a lot of development time and frustration. > This doesn't mean there isn't a benefit to finding the perfect regular > expression for your needs, just that it can often be difficult to guarantee > your code won't be plagued by false matches or false exclusions as your > expression becomes more and more complex. > > Hope this helps a little. > > Much warmth, > > Murray > --- > "Lost in thought..." > http://www.planetthoughtful.org -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
