I don't have a deep knowledge of regular expressions (I just learned it today). I have a website and I want to ask how I create a 6 digit security code either in the form of:
1. LNLNLN
or
2. NLNLNL
Where L = Letter and N = Number
I am not sure of the best way to do this, but I have seen people using preg_match() to validate data. I found that using this regular expression works:
^[a-zA-Z][0-9][a-zA-Z][0-9][a-zA-Z][0-9]|^[0-9][a-zA-Z][0-9][a-zA-Z][0-9][a-zA-Z]
but this seems pretty long. I wonder if there is any way that I can check this more easily? Thank you
Use repetition
^([a-zA-Z][0-9]){3}|^([0-9][a-zA-Z]){3}
Then escape sequence \d
^([a-zA-Z]\d){3}|^(\d[a-zA-Z]){3}
With i option you can write even this.
^([a-z]\d){3}|^(\d[a-z]){3}
preg_match('/^([a-z]\d){3}|^(\d[a-z]){3}/i', $string)
Related
Hello everyone I'm trying to validate if input has correct data. I need to check it input is number in pattern xx,xx or xxx. For example if user put 100 or 120,32 it will pass the validation. I'm trying to make regular expression for this but I'm not good in this topic. I have working code for xx,xx but how can I add to check first or second option to don't throw an error? Here is what I've got:
/^[+]?\d+\,\d+/
Your question
For the examples you mentioned, this would match all occurences:
/\d{2,3}(,\d{2})?)/
It says (in basic english): Two to three digits, followed by an optional "comma and two digits". For explanation, also see the example on Regex101: https://regex101.com/r/hU5kJ7/1
However I do not see any reason why you would limit the digits before the floating point to 3 digits, so to make it open, you could just leave out the 3:
/\d{2,}(,\d{2})?)/
It says (in basic english): Two to unlimited digits, followed by an optional "comma and two digits".
Apart from that
I would really not recommend implementing something that basic like number (or currency?) validation by yourself again. It is like reinventing the wheel. You will find many and many validation implementations like that all over the internet, in so called validation libraries or frameworks.
This regex should solve your problem:
/^\d+(,\d+)?/
For some reason I always get stuck making anything past extremely basic regular expressions.
I'm trying to make a regular expression that kind of looks like a URL. I only want basic checking.
I would like it to match the following patterns where X is "something".
X://X.X
X://X.X... etc.
X.X
X.X... etc
If the string contains one of these patterns, it is sufficient checking for me. This way a url like www.example.com:8888 will still match. I have tried many different REGEX combinations with preg_match and cannot seem to get any to behave the way I want it to. I have consulted many other related REGEX questions on SO but my readings have not helped me.
Any help? I will be happy to provide more information if you would like but I don't know what else you would need.
It takes practice but here is one that I made using a regex tester (http://www.regextester.com/) to check my pattern:
^.+(:\/\/|\.)([a-zA-Z0-9]+\.)+.+
My approach is to slowly build my pattern from the beginning and add on one piece at a time. This cheatsheet is extremely helpful for remembering http://www.cheatography.com/davechild/cheat-sheets/regular-expressions/ what everything is.
Basically the pattern starts at the beginning of the string and checks for any characters followed by either :// or . then checks for groupings of letters and numbers followed by a . ending with any number of characters.
The pattern could probably be improved with groupings to not pass on invalid characters. But this one was quick and dirty. You could replace the first and last . with the characters that would be valid.
UPDATE
Per the comments here is an updated pattern:
^.+?(:\/\/|\.)?([a-zA-Z0-9]+?\.)+.+
/^(.+:\/\/)?[^.]+\.[^.\/]+([.\/][^.\/]+)*$/
I am trying to create a single regular expression that I can use to extract the number from two different urls in a PHP function. The format of these urls are:
/t/2121/title/
and
/top2121.html
I am bad at regular expressions and have already tried the following and many variants of it:
#^/t/(\d+?)/|/top(\d+?)\.html/#i
This is not doing anything and I am still at a complete loss after reading many sites and tutorials on regular expressions. Is there a regular expression I could create that would allow me to extra the number regardless of the url format entered?
Regex to extract only the digits while also checking if url matches accepted formats:
#^\/t(?:\/(\d+)\/[a-z_-]+\/?|op(\d+)\.html)$#i edit: captures in 2 groups
Explained demo here: http://regex101.com/r/dO5dI4
Variant #2: captures in the same group
#^\/t(?|\/(\d+)\/[a-z_-]+\/?$|op(\d+)\.html$)#i
Explained demo here: http://regex101.com/r/cG9vC3
if you just want the first digits after t regardless of the / between, something like this might work: #t/?(\d+)#i
edit:
example: http://codepad.viper-7.com/0z3ee0
I was able to get this regexp to match both types of url formats:
#^/(?:(?:t/)|(?:top))(\d+)(?:(?:\.html)|(?:/))#i
If anyone has a more efficient way of performing the same regexp, I would love to hear it.
If you got either one of these URL's you could use this expression. Your numbers should be stored in your second position:
#^/t(op|/)(\d+)(\.html|/.*)#i
Are there ever going to be numbers in the URL that you don't care about? If not, you can keep this simple by just capturing the numbers and ignoring the rest:
#(\d+)#
Is it possible to display the strings that match a regular expression?
Example:
Take the expression /^AD\d{3}/
and display AD999
What I'm doing is validating a string that is pretty simple either containing all numbers, a few characters maybe, and maybe a '-'. I am validating a postal code on form submit against a database of all countries that use a postal code.
I could perform it in Javascript or PHP, if that makes any difference.
No. That sort of feature is not available.
You can try to implement it yourself, but I don't think that's the solution for you. Simply write the messages normally. Not everything must always be dynamic.
I like your way of thinking though.
It is possible. The developers of PEX figured it out.
Don't get your hopes up, I don't know of any javascript implementation.
There is one for javascript now: http://fent.github.io/randexp.js/.
I have understood your problem a little better from your additional comments.
Since your data is only postal codes, I suggest that it would possible to work in the other direction and store a picture in the database and automatically generate a regex from that.
For instance, UK postcodes look like AA?99? 9AA | AA?9A 9AA which is easily converted to a regex (using a regex!).
I wouldn't call myself a master regarding regex, i pretty much just know the basics. I've been playing around with it, but i can't seem to get the desired result. So if someone would help me, i would really appreciate it!
I'm trying to check wether unwanted words exist in a string. I'm working on a math project, and i'm gonna be using eval() to calculate the string, so i need to make sure it's safe.
The string may contain (just for example now, i'll add more functions later) the following words: (read the comments)
floor() // spaces or numbers are allowed between the () chars. If possible, i'd also like to allow other math functions inside, so it'd look like: floor( floor(8)*1 ).
It may contain any digit, any math sign (+ - * /) and dots/commas (,.) anywhere in the string
Just to be clear, here's another example: If a string like this is passed, i do not want it to pass:
9*9 + include('somefile') / floor(2) // Just a random example on something that's not allowed
Now that i think about it, it looks kind of complicated. I hope you can at least give me some hints.
Thanks in advance,
-Anthony
Edit: This is a bit off-topic, but if you know a better way of calculating math functions, please suggest it. I've been looking for a safe math class/function that calculates an input string, but i haven't found one yet.
Please do not use eval() for this.
My standard answer to this question whenever it crops up:
Don't use eval (especially if the formula contains user input) or reinvent the wheel by writing your own formula parser.
Take a look at the evalMath class on PHPClasses. It should do everything that you want in a nice safe sandbox.
To rephrase your problem, you want to allow only a specific set of characters, plus certain predefined words. The alternation operator (pipe symbol) is your friend in this case:
([0-9\+\-\*\/\.\,\(\) ]|floor|ceiling|other|functions)*
Of course, using eval is inherently dangerous, and it is difficult to guarantee that this regex will offer full protection in a language with syntax as expansive as PHP.