I'm trying to make a replace in a string with a regex, and I really hope the community can help me.
I have this string :
031,02a,009,a,aaa,AZ,AZE,02B,975,135
And my goal is to remove the opposite of this regex
[09][0-9]{2}|[09][0-9][A-Za-z]
i.e.
a,aaa,AZ,AZE,135
(to see it in action : http://regexr.com?3795f )
My final goal is to preg_replace the first string to only get
031,02a,009,02B,975
(to see it in action : http://regexr.com?3795f )
I'm open to all solution, but I admit that I really like to make this work with a preg_replace if it's possible (It became something like a personnal challenge)
Thanks for all help !
As #Taemyr pointed out in comments, my previous solution (using a lookbehind assertion) was incorrect, as it would consume 3 characters at a time even while substrings weren't always 3 characters.
Let's use a lookahead assertion instead to get around this:
'/(^|,)(?![09][0-9]{2}|[09][0-9][A-Za-z])[^,]*/'
The above matches the beginning of the string or a comma, then checks that what follows does not match one of the two forms you've specified to keep, and given that this condition passes, matches as many non-comma characters as possible.
However, this is identical to #anubhava's solution, meaning it has the same weakness, in that it can leave a leading comma in some cases. See this Ideone demo.
ltriming the comma is the clean way to go there, but then again, if you were looking for the "clean way to go," you wouldn't be trying to use a single preg_replace to begin with, right? Your question is whether it's possible to do this without using any other PHP functions.
The anwer is yes. We can take
'/(^|,)foo/'
and distribute the alternation,
'/^foo|,foo/'
so that we can tack on the extra comma we wish to capture only in the first case, i.e.
'/^foo,|,foo/'
That's going to be one hairy expression when we substitute foo with our actual regex, isn't it. Thankfully, PHP supports recursive patterns, so that we can rewrite the above as
'/^(foo),|,(?1)/'
And there you have it. Substituting foo for what it is, we get
'/^((?![09][0-9]{2}|[09][0-9][A-Za-z])[^,]*),|,(?1)/'
which indeed works, as shown in this second Ideone demo.
Let's take some time here to simplify your expression, though. [0-9] is equivalent to \d, and you can use case-insensitive matching by adding /i, like so:
'/^((?![09]\d{2}|[09]\d[a-z])[^,]*),|,(?1)/i'
You might even compact the inner alternation:
'/^((?![09]\d(\d|[a-z]))[^,]*),|,(?1)/i'
Try it in more steps:
$newList = array();
foreach (explode(',', $list) as $element) {
if (!preg_match('/[09][0-9]{2}|[09][0-9][A-Za-z]/', $element) {
$newList[] = $element;
}
}
$list = implode(',', $newList);
You still have your regex, see! Personnal challenge completed.
Try matching what you want to keep and then joining it with commas:
preg_match_all('/[09][0-9]{2}|[09][0-9][A-Za-z]/', $input, $matches);
$result = implode(',', $matches);
The problem you'll be facing with preg_replace is the extra-commas you'll have to strip, cause you don't just want to remove aaa, you actually want to remove aaa, or ,aaa. Now what when you have things to remove both at the beginning and at the end of the string? You can't just say "I'll just strip the comma before", because that might lead to an extra comma at the beginning of the string, and vice-versa. So basically, unless you want to mess with lookaheads and/or lookbehinds, you'd better do this in two steps.
This should work for you:
$s = '031,02a,009,a,aaa,AZ,AZE,02B,975,135';
echo ltrim(preg_replace('/(^|,)(?![09][0-9]{2}|[09][0-9][A-Za-z])[^,]+/', '', $s), ',');
OUTPUT:
031,02a,009,02B,975
Try this:
preg_replace('/(^|,)[1-8a-z][^,]*/i', '', $string);
this will remove all substrings starting with the start of the string or a comma, followed by a non allowed first character, up to but excluding the following comma.
As per #GeoffreyBachelet suggestion, to remove residual commas, you should do:
trim(preg_replace('/(^|,)[1-8a-z][^,]*/i', '', $string), ',');
I have the string 562865_numbersletterssymbols
If I want to delete, IF EXISTS; the first part (562865_), what should I search?
My guess was ^[^?:(562865_)]+$ to take what was not "562865_" (if existing ?:) until $ +$
But I discovered that (562865_) searchs every single digit and not the whole string.
How can I find the solution?
The easiest way that I was able to come up with is this. It will work not only for that name but any others with the same format.
<?php
$string = "562865_numbersletterssymbols";
echo preg_replace("/^\d+_/", "", $string);
If you want to stick with regex, try ^[\d]+_(.+)$
the _ splits the string into 2 parts, and you need the second part in parenthesis (.+)
Thanks to raina77ow, the easiest way is always the best choice.
$your_var = str_replace('562865_', '', $your_var)
I was just thinking that how could we group by or seperate similar words in PHP or MYSQL. For instance, like i have samsung Glaxy Ace, Is this possible to recognize S120, S-120, s120, S-120.
Is this even possible?
Thanks
What you could do is strip all non alphanumeric characters and spaces, and strtoupper() the string.
$new_string = preg_replace("/[^a-zA-Z0-9]/", "", $string);
$new_string = strtoupper($new_string);
Only those? Easily.
/S-?120/i
But if you want to extend, you'll probably need to move from REGEX to something a little more sophisticated.
The best thing to do here is to pick a format and standardise on it. So for your example, you would just store S120, and when you get a value from a user, strip all non-alphanumeric characters from it and convert it to upper case.
You can do this in PHP with this code:
$result = strtoupper(preg_replace('/(\W|_)+/', '', $userInput));
Let say I have the following string:
getPasswordLastChangedDatetime
How would I be able to split that up by capital letters so that I would be able to get:
get
Password
Last
Changed
Datetime
If you only care about ASCII characters:
$parts = preg_split("/(?=[A-Z])/", $str);
DEMO
The (?= ..) construct is called lookahead [docs].
This works if the parts only contain a capital character at the beginning. It gets more complicated if you have things like getHTMLString. This could be matched by:
$parts = preg_split("/((?<=[a-z])(?=[A-Z])|(?=[A-Z][a-z]))/", $str);
DEMO
Asked this a little too soon, found this:
preg_replace('/(?!^)[[:upper:]]/',' \0',$test);
For instance:
(?:^|\p{Lu})\P{Lu}*
No need to over complicated solution. This does it
preg_replace('/([A-Z])/',"\n".'$1',$string);
This doens't take care of acronyms of course
Use this: [a-z]+|[A-Z][a-z]* or \p{Ll}+|\p{Lu}\p{Ll}*
preg_split("/(?<=[a-z])(?=[A-Z])/",$password));
preg_split('#(?=[A-Z])#', 'asAs')
i'v got such string <>1 <>2 <>3
i want remove all '<>' and symbols after '<>' i want replace with such expression like www.test.com/1.jpg, www.test.com/2.jpg, www.test.com/3.jpg
is it possible to do with regex? i only know to find '/<>.?/'
preg_replace('/<>(\d+)/g', 'www.test.com/bla/$1.jpg', $input);
(assuming your replaced elements are just numbers. If they are more general, you'll need to replace '\d+' by something else).
str_replace('<>', 'www.test.com/', $input);
// pseudo code
pre_replace_all('~<>([0-9]+)~', 'www.test.com/$1.jpg', $input);
$string = '<>1 <>2 <>3';
$temp = explode(' ',preg_replace('/<>(\d)/','www.test.com/\1.jpg',$string));
$newString = implode(', ',$temp);
echo $newString;
Based on your example, I don’t think you need regex at all.
$str = '<>1 <>2 <>3';
print_r(str_replace('<>', 'www.test.com/', $str));
Regex's allow you to manipulate a string in any fashion you desire, to modify the string in the fashion you desire you would use the following regex:
<>(\d)
and you would use regex back referencing to keep the values you have captured in your grouping brackets, in this case a single digit. The back reference is typically signified by the $ symbol and then the number of the group you are referencing. As follows:
www.test.com/$1
this would be used in a regex replace scenario which would be implemented in different ways depending on the language you are implementing your regex replace method in.