There has always been a confusion with preg_match in php.
I have a string like this:
apsd_01_03s_somedescription
apsd_02_04_somedescription
Can I use preg_match to strip off anything from 3rd underscore including the 3rd underscore.
thanks.
Try this:
preg_replace('/^([^_]*_[^_]*_[^_]*).*/', '$1', $str)
This will take only the first three sequences that are separated by _. So everything from the third _ on will be removed.
if you want to strip the "_somedescription" part: preg_replace('/([^]*)([^]*)([^]*)(.*)/', '$1_$2_$3', $str);
I agree with Gumbo's answer, however, instead of using regular expressions, you can use PHP's array functions:
$s = "apsd_01_03s_somedescription";
$parts = explode("_", $s);
echo implode("_", array_slice($parts, 0, 3));
// apsd_01_03s
This method appears to execute similarly in speed, compared to a regular expression solution.
If the third underscore is the last one, you can do this:
preg_replace('/^(.+)_.+?)$/', $1, $str);
Related
I have three types of strings that I encounter. My goal is to cycle through all of them and just get name.
page_1.name
page_2.name.text
page_1.name.something
The only way I can figure out doing this is to first remove the page_# with the following:
$remove_page = preg_replace("/(page_\d+\.)(\w+)/", "$2", $string);
Then remove the last bit like so:
$get_name = preg_replace("/(\w+)(\.\w+)/", "$1", $remove_page);
Is there a more efficient way to do this? This works, but I feel like I'm only slightly grasping the power of regex.
You can use this regex:
preg_match('/(?<=page_\d\.)[^.]+/', $input, $matches);
(?<=page_\d\.) is a lookbehind that makes sure our match is preceded by page_ and a digit. [^.]+ will match 1 or more characters that are not DOT.
RegEx Demo
Otherwise split by DOT and take 1st element:
$arr = explode('.', $input);
$name = $arr[1];
How can I replace a string starting with 'a' and ending with 'z'?
basically I want to be able to do the same thing as str_replace but be indifferent to the values in between two strings in a 'haystack'.
Is there a built in function for this? If not, how would i go about efficiently making a function that accomplishes it?
That can be done with Regular Expression (RegEx for short).
Here is a simple example:
$string = 'coolAfrackZInLife';
$replacement = 'Stuff';
$result = preg_replace('/A.*Z/', $replacement, $string);
echo $result;
The above example will return coolStuffInLife
A little explanation on the givven RegEx /A.*Z/:
- The slashes indicate the beginning and end of the Regex;
- A and Z are the start and end characters between which you need to replace;
- . matches any single charecter
- * Zero or more of the given character (in our case - all of them)
- You can optionally want to use + instead of * which will match only if there is something in between
Take a look at Rubular.com for a simple way to test your RegExs. It also provides short RegEx reference
$string = "I really want to replace aFGHJKz with booo";
$new_string = preg_replace('/a[a-zA-z]+z/', 'boo', $string);
echo $new_string;
Be wary of the regex, are you wanting to find the first z or last z? Is it only letters that can be between? Alphanumeric? There are various scenarios you'd need to explain before I could expand on the regex.
use preg_replace so you can use regex patterns.
For example, if I wanted to preg_replace the title of a HTML element:
$str = preg_replace('/title=\"([^\"]+)\"/', 'foo', $str);
Please do not give me other solutions (non regex) for this specific example, this is merely an example. I need a solution that works for any regular expressions.
If you want to match parts with preg_replace, but only partially replace something else, then there are two options.
Either you just reinsert the matched parts (enclose in capture groups, and then use $1 and $3):
$str = preg_replace('/(title=")([^"]+)(")/', '$1foo$3', $str);
Or you use assertions:
$str = preg_replace('/(?<=title=")([^"]+)(?=")/', 'foo', $str);
Say I have the following string:
$str = "Hello, my name is Bob and I like 'pizza'. Do you like pizza??"
Currently I am able to split/explode this string on the whitespace using:
$arr = explode(' ', $str);
but I want to use the regex pattern \W like so:
$arr = explode('\W', $str);
This should separate all words that aren't punctuation, allowing the 'pizza' part to be separated as pizza. Except it returns nothing (I get an empty array back).
What can I do?
Use preg_split:
http://www.php.net/manual/en/function.preg-split.php
explode does not do Regexen.
preg_split does.
You should use preg_split instead of explode
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.