I'm not very good at regular expressions at all.
I've been using a lot of framework code to date, but I'm unable to find one that is able to match a URL like http://www.example.com/etcetc, but it is also is able to catch something like www.example.com/etcetc and example.com/etcetc.
For matching all kinds of URLs, the following code should work:
<?php
$regex = "((https?|ftp)://)?"; // SCHEME
$regex .= "([a-z0-9+!*(),;?&=$_.-]+(:[a-z0-9+!*(),;?&=$_.-]+)?#)?"; // User and Pass
$regex .= "([a-z0-9\-\.]*)\.(([a-z]{2,4})|([0-9]{1,3}\.([0-9]{1,3})\.([0-9]{1,3})))"; // Host or IP address
$regex .= "(:[0-9]{2,5})?"; // Port
$regex .= "(/([a-z0-9+$_%-]\.?)+)*/?"; // Path
$regex .= "(\?[a-z+&\$_.-][a-z0-9;:#&%=+/$_.-]*)?"; // GET Query
$regex .= "(#[a-z_.-][a-z0-9+$%_.-]*)?"; // Anchor
?>
Then, the correct way to check against the regex is as follows:
<?php
if(preg_match("~^$regex$~i", 'www.example.com/etcetc', $m))
var_dump($m);
if(preg_match("~^$regex$~i", 'http://www.example.com/etcetc', $m))
var_dump($m);
?>
Courtesy: Comments made by splattermania in the PHP manual: preg_match
RegEx Demo in regex101
This worked for me in all cases I had tested:
$url_pattern = '/((http|https)\:\/\/)?[a-zA-Z0-9\.\/\?\:#\-_=#]+\.([a-zA-Z0-9\&\.\/\?\:#\-_=#])*/';
Tests:
http://test.test-75.1474.stackoverflow.com/
https://www.stackoverflow.com
https://www.stackoverflow.com/
http://wwww.stackoverflow.com/
http://wwww.stackoverflow.com
http://test.test-75.1474.stackoverflow.com/
http://www.stackoverflow.com
http://www.stackoverflow.com/
stackoverflow.com/
stackoverflow.com
http://www.example.com/etcetc
www.example.com/etcetc
example.com/etcetc
user:pass#example.com/etcetc
example.com/etcetc?query=aasd
example.com/etcetc?query=aasd&dest=asds
http://stackoverflow.com/questions/6427530/regular-expression-pattern-to-match-url-with-or-without-http-www
http://stackoverflow.com/questions/6427530/regular-expression-pattern-to-match-url-with-or-without-http-www/
Every valid Internet URL has at least one dot, so the above pattern will simply try to find any at least two strings chained by a dot and has valid characters that URL may have.
Try this:
/^http:\/\/|(www\.)?[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$/
It works exactly like the people want.
It takes with or with out http://, https://, and www.
You can use a question mark after a regular expression to make it conditional so you would want to use:
http:\/\/(www\.)?
That will match anything that has either http://www. or http:// (with no www.)
You could just use a replace method to remove the above, thus getting you the domain. It depends on what you need the domain for.
Try something like this:
.*([\w-]+\.)+[a-z]{2,5}(/[\w-]+)*
Use:
/(https?://)?((?:(\w+-)*\w+)\.)+(?:[a-z]{2})(\/?\w?-?=?_?\??&?)+[\.]?([a-z0-9\?=&_\-%#])?/g
It matches something.com, http(s):// or www. It does not match other [something]:// URLs though, but for my purpose that's not necessary.
The regex matches e.g.:
http://foo.co.uk/
www.regex.com/foo.html?q=bar$some=thi-ng,regex
regex.foo.com/blog
You can try this:
r"(http[s]:\/\/)?([\w-]+\.)+([a-z]{2,5})(\/+\w+)? "
Selection:
may be start with http:// or https:// (optional)
anything (word) end with dot (.)
followed by 2 to 5 character [a-z]
followed by "/[anything]" (optional)
followed by space
Try this
$url_reg = /(ftp|https?):\/\/(\w+:?\w*#)?(\S+)(:[0-9]+)?(\/([\w#!:.?+=&%#!\/-])?)?/;
I have been using the following, which works for all my test cases, as well as fixes any issues where it would trigger at the end of a sentence preceded by a full-stop (end.), or where there were single character initials, such as 'C.C. Plumbing'.
The following regex contains multiple {2,}s, which means two or more matches of the previous pattern.
((http|https)\:\/\/)?[a-zA-Z0-9\.\/\?\:#\-_=#]{2,}\.([a-zA-Z0-9\&\.\/\?\:#\-_=#]){2,}
Matches URLs such as, but not limited to:
https://example.com
http://example.com
example.com
example.com/test
example.com?value=test
Does not match non-URLs such as, but not limited to:
C.C Plumber
A full-stop at the end of a sentence.
Single characters such as a.b or x.y
Please note: Due to the above, this will not match any single character URLs, such as: a.co, but it will match if it is preceded by a URL scheme, such as: http://a.co.
I was getting so many issues getting the answer from anubhava to work due to recent PHP allowing $ in strings and the preg match wasn't working.
Here is what I used:
// Regular expression
$re = '/((https?|ftp):\/\/)?([a-z0-9+!*(),;?&=.-]+(:[a-z0-9+!*(),;?&=.-]+)?#)?([a-z0-9\-\.]*)\.(([a-z]{2,4})|([0-9]{1,3}\.([0-9]{1,3})\.([0-9]{1,3})))(:[0-9]{2,5})?(\/([a-z0-9+%-]\.?)+)*\/?(\?[a-z+&$_.-][a-z0-9;:#&%=+\/.-]*)?(#[a-z_.-][a-z0-9+$%_.-]*)?/i';
// Match all
preg_match_all($re, $blob, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
// The first element of the array is the full match
This PHP Composer package URL highlight is doing a good job in PHP:
<?php
use VStelmakh\UrlHighlight\UrlHighlight;
$urlHighlight = new UrlHighlight();
$matches = $urlHighlight->getUrls($string);
?>
If it does not have to be regex, you could always use the validate filters that are in PHP.
filter_var('http://example.com', FILTER_VALIDATE_URL);
filter_var (mixed $variable [, int $filter = FILTER_DEFAULT [, mixed $options ]]);
Types of Filters
Validate Filters
Regex if you want to ensure a URL starts with HTTP/HTTPS:
https?:\/\/(www\.)?[-a-zA-Z0-9#:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()#:%_\+.~#?&//=]*)
If you do not require the HTTP protocol:
[-a-zA-Z0-9#:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()#:%_\+.~#?&//=]*)
Related
I have this link, and i need to work only with the numbers from that link.
How would i extract them?
I didn't find any answer that would work with codepcetion.
https://www.my-website.com/de/booking/extras#tab-nav-extras-1426
I tired something like this.
$I->grabFromCurrentUrl('\d+');
But i won't work.
Any ideas ?
Staying within the framework:
The manual clearly says that:
grabFromCurrentUrl
Executes the given regular expression against the current URI and
returns the first capturing group. If no parameters are provided, the
full URI is returned.
Since you didn't used any capturing groups (...), nothing is returned.
Try this:
$I->grabFromCurrentUrl('~(\d+)$~');
The $ at the end is optional, it just states that the string should end with the pattern.
Also note that the opening and closing pattern delimiters you would normally use (/) are replaced by tilde (~) characters for convenience, since the input string has a great chance to contain multiple forward slashes. Custom pattern delimiters are completely standard in regexp, as #Naktibalda pointed it out in this answer.
You can use parse_url() to parse entire URL and then extract the part which is most interested for you. After that you can use regex to extract only numbers from the string.
$url = "https://www.my-website.com/de/booking/extras#tab-nav-extras-1426";
$parsedUrl = parse_url($url);
$fragment = $parsedUrl['fragment']; // Contains: tab-nav-extras-1426
$id = preg_replace('/[^0-9]/', '', $fragment);
var_dump($id); // Output: string(4) "1426"
A variant using preg_match() after parse_url():
$url = "https://www.my-website.com/de/booking/extras#tab-nav-extras-1426";
preg_match('/\d+$/', parse_url($url)['fragment'], $id);
var_dump($id[0]);
// Outputs: string(4) "1426"
I'm not very good at regular expressions at all.
I've been using a lot of framework code to date, but I'm unable to find one that is able to match a URL like http://www.example.com/etcetc, but it is also is able to catch something like www.example.com/etcetc and example.com/etcetc.
For matching all kinds of URLs, the following code should work:
<?php
$regex = "((https?|ftp)://)?"; // SCHEME
$regex .= "([a-z0-9+!*(),;?&=$_.-]+(:[a-z0-9+!*(),;?&=$_.-]+)?#)?"; // User and Pass
$regex .= "([a-z0-9\-\.]*)\.(([a-z]{2,4})|([0-9]{1,3}\.([0-9]{1,3})\.([0-9]{1,3})))"; // Host or IP address
$regex .= "(:[0-9]{2,5})?"; // Port
$regex .= "(/([a-z0-9+$_%-]\.?)+)*/?"; // Path
$regex .= "(\?[a-z+&\$_.-][a-z0-9;:#&%=+/$_.-]*)?"; // GET Query
$regex .= "(#[a-z_.-][a-z0-9+$%_.-]*)?"; // Anchor
?>
Then, the correct way to check against the regex is as follows:
<?php
if(preg_match("~^$regex$~i", 'www.example.com/etcetc', $m))
var_dump($m);
if(preg_match("~^$regex$~i", 'http://www.example.com/etcetc', $m))
var_dump($m);
?>
Courtesy: Comments made by splattermania in the PHP manual: preg_match
RegEx Demo in regex101
This worked for me in all cases I had tested:
$url_pattern = '/((http|https)\:\/\/)?[a-zA-Z0-9\.\/\?\:#\-_=#]+\.([a-zA-Z0-9\&\.\/\?\:#\-_=#])*/';
Tests:
http://test.test-75.1474.stackoverflow.com/
https://www.stackoverflow.com
https://www.stackoverflow.com/
http://wwww.stackoverflow.com/
http://wwww.stackoverflow.com
http://test.test-75.1474.stackoverflow.com/
http://www.stackoverflow.com
http://www.stackoverflow.com/
stackoverflow.com/
stackoverflow.com
http://www.example.com/etcetc
www.example.com/etcetc
example.com/etcetc
user:pass#example.com/etcetc
example.com/etcetc?query=aasd
example.com/etcetc?query=aasd&dest=asds
http://stackoverflow.com/questions/6427530/regular-expression-pattern-to-match-url-with-or-without-http-www
http://stackoverflow.com/questions/6427530/regular-expression-pattern-to-match-url-with-or-without-http-www/
Every valid Internet URL has at least one dot, so the above pattern will simply try to find any at least two strings chained by a dot and has valid characters that URL may have.
Try this:
/^http:\/\/|(www\.)?[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$/
It works exactly like the people want.
It takes with or with out http://, https://, and www.
You can use a question mark after a regular expression to make it conditional so you would want to use:
http:\/\/(www\.)?
That will match anything that has either http://www. or http:// (with no www.)
You could just use a replace method to remove the above, thus getting you the domain. It depends on what you need the domain for.
Try something like this:
.*([\w-]+\.)+[a-z]{2,5}(/[\w-]+)*
Use:
/(https?://)?((?:(\w+-)*\w+)\.)+(?:[a-z]{2})(\/?\w?-?=?_?\??&?)+[\.]?([a-z0-9\?=&_\-%#])?/g
It matches something.com, http(s):// or www. It does not match other [something]:// URLs though, but for my purpose that's not necessary.
The regex matches e.g.:
http://foo.co.uk/
www.regex.com/foo.html?q=bar$some=thi-ng,regex
regex.foo.com/blog
You can try this:
r"(http[s]:\/\/)?([\w-]+\.)+([a-z]{2,5})(\/+\w+)? "
Selection:
may be start with http:// or https:// (optional)
anything (word) end with dot (.)
followed by 2 to 5 character [a-z]
followed by "/[anything]" (optional)
followed by space
Try this
$url_reg = /(ftp|https?):\/\/(\w+:?\w*#)?(\S+)(:[0-9]+)?(\/([\w#!:.?+=&%#!\/-])?)?/;
I have been using the following, which works for all my test cases, as well as fixes any issues where it would trigger at the end of a sentence preceded by a full-stop (end.), or where there were single character initials, such as 'C.C. Plumbing'.
The following regex contains multiple {2,}s, which means two or more matches of the previous pattern.
((http|https)\:\/\/)?[a-zA-Z0-9\.\/\?\:#\-_=#]{2,}\.([a-zA-Z0-9\&\.\/\?\:#\-_=#]){2,}
Matches URLs such as, but not limited to:
https://example.com
http://example.com
example.com
example.com/test
example.com?value=test
Does not match non-URLs such as, but not limited to:
C.C Plumber
A full-stop at the end of a sentence.
Single characters such as a.b or x.y
Please note: Due to the above, this will not match any single character URLs, such as: a.co, but it will match if it is preceded by a URL scheme, such as: http://a.co.
I was getting so many issues getting the answer from anubhava to work due to recent PHP allowing $ in strings and the preg match wasn't working.
Here is what I used:
// Regular expression
$re = '/((https?|ftp):\/\/)?([a-z0-9+!*(),;?&=.-]+(:[a-z0-9+!*(),;?&=.-]+)?#)?([a-z0-9\-\.]*)\.(([a-z]{2,4})|([0-9]{1,3}\.([0-9]{1,3})\.([0-9]{1,3})))(:[0-9]{2,5})?(\/([a-z0-9+%-]\.?)+)*\/?(\?[a-z+&$_.-][a-z0-9;:#&%=+\/.-]*)?(#[a-z_.-][a-z0-9+$%_.-]*)?/i';
// Match all
preg_match_all($re, $blob, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
// The first element of the array is the full match
This PHP Composer package URL highlight is doing a good job in PHP:
<?php
use VStelmakh\UrlHighlight\UrlHighlight;
$urlHighlight = new UrlHighlight();
$matches = $urlHighlight->getUrls($string);
?>
If it does not have to be regex, you could always use the validate filters that are in PHP.
filter_var('http://example.com', FILTER_VALIDATE_URL);
filter_var (mixed $variable [, int $filter = FILTER_DEFAULT [, mixed $options ]]);
Types of Filters
Validate Filters
Regex if you want to ensure a URL starts with HTTP/HTTPS:
https?:\/\/(www\.)?[-a-zA-Z0-9#:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()#:%_\+.~#?&//=]*)
If you do not require the HTTP protocol:
[-a-zA-Z0-9#:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()#:%_\+.~#?&//=]*)
I'm not very good at regular expressions at all.
I've been using a lot of framework code to date, but I'm unable to find one that is able to match a URL like http://www.example.com/etcetc, but it is also is able to catch something like www.example.com/etcetc and example.com/etcetc.
For matching all kinds of URLs, the following code should work:
<?php
$regex = "((https?|ftp)://)?"; // SCHEME
$regex .= "([a-z0-9+!*(),;?&=$_.-]+(:[a-z0-9+!*(),;?&=$_.-]+)?#)?"; // User and Pass
$regex .= "([a-z0-9\-\.]*)\.(([a-z]{2,4})|([0-9]{1,3}\.([0-9]{1,3})\.([0-9]{1,3})))"; // Host or IP address
$regex .= "(:[0-9]{2,5})?"; // Port
$regex .= "(/([a-z0-9+$_%-]\.?)+)*/?"; // Path
$regex .= "(\?[a-z+&\$_.-][a-z0-9;:#&%=+/$_.-]*)?"; // GET Query
$regex .= "(#[a-z_.-][a-z0-9+$%_.-]*)?"; // Anchor
?>
Then, the correct way to check against the regex is as follows:
<?php
if(preg_match("~^$regex$~i", 'www.example.com/etcetc', $m))
var_dump($m);
if(preg_match("~^$regex$~i", 'http://www.example.com/etcetc', $m))
var_dump($m);
?>
Courtesy: Comments made by splattermania in the PHP manual: preg_match
RegEx Demo in regex101
This worked for me in all cases I had tested:
$url_pattern = '/((http|https)\:\/\/)?[a-zA-Z0-9\.\/\?\:#\-_=#]+\.([a-zA-Z0-9\&\.\/\?\:#\-_=#])*/';
Tests:
http://test.test-75.1474.stackoverflow.com/
https://www.stackoverflow.com
https://www.stackoverflow.com/
http://wwww.stackoverflow.com/
http://wwww.stackoverflow.com
http://test.test-75.1474.stackoverflow.com/
http://www.stackoverflow.com
http://www.stackoverflow.com/
stackoverflow.com/
stackoverflow.com
http://www.example.com/etcetc
www.example.com/etcetc
example.com/etcetc
user:pass#example.com/etcetc
example.com/etcetc?query=aasd
example.com/etcetc?query=aasd&dest=asds
http://stackoverflow.com/questions/6427530/regular-expression-pattern-to-match-url-with-or-without-http-www
http://stackoverflow.com/questions/6427530/regular-expression-pattern-to-match-url-with-or-without-http-www/
Every valid Internet URL has at least one dot, so the above pattern will simply try to find any at least two strings chained by a dot and has valid characters that URL may have.
Try this:
/^http:\/\/|(www\.)?[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$/
It works exactly like the people want.
It takes with or with out http://, https://, and www.
You can use a question mark after a regular expression to make it conditional so you would want to use:
http:\/\/(www\.)?
That will match anything that has either http://www. or http:// (with no www.)
You could just use a replace method to remove the above, thus getting you the domain. It depends on what you need the domain for.
Try something like this:
.*([\w-]+\.)+[a-z]{2,5}(/[\w-]+)*
Use:
/(https?://)?((?:(\w+-)*\w+)\.)+(?:[a-z]{2})(\/?\w?-?=?_?\??&?)+[\.]?([a-z0-9\?=&_\-%#])?/g
It matches something.com, http(s):// or www. It does not match other [something]:// URLs though, but for my purpose that's not necessary.
The regex matches e.g.:
http://foo.co.uk/
www.regex.com/foo.html?q=bar$some=thi-ng,regex
regex.foo.com/blog
You can try this:
r"(http[s]:\/\/)?([\w-]+\.)+([a-z]{2,5})(\/+\w+)? "
Selection:
may be start with http:// or https:// (optional)
anything (word) end with dot (.)
followed by 2 to 5 character [a-z]
followed by "/[anything]" (optional)
followed by space
Try this
$url_reg = /(ftp|https?):\/\/(\w+:?\w*#)?(\S+)(:[0-9]+)?(\/([\w#!:.?+=&%#!\/-])?)?/;
I have been using the following, which works for all my test cases, as well as fixes any issues where it would trigger at the end of a sentence preceded by a full-stop (end.), or where there were single character initials, such as 'C.C. Plumbing'.
The following regex contains multiple {2,}s, which means two or more matches of the previous pattern.
((http|https)\:\/\/)?[a-zA-Z0-9\.\/\?\:#\-_=#]{2,}\.([a-zA-Z0-9\&\.\/\?\:#\-_=#]){2,}
Matches URLs such as, but not limited to:
https://example.com
http://example.com
example.com
example.com/test
example.com?value=test
Does not match non-URLs such as, but not limited to:
C.C Plumber
A full-stop at the end of a sentence.
Single characters such as a.b or x.y
Please note: Due to the above, this will not match any single character URLs, such as: a.co, but it will match if it is preceded by a URL scheme, such as: http://a.co.
I was getting so many issues getting the answer from anubhava to work due to recent PHP allowing $ in strings and the preg match wasn't working.
Here is what I used:
// Regular expression
$re = '/((https?|ftp):\/\/)?([a-z0-9+!*(),;?&=.-]+(:[a-z0-9+!*(),;?&=.-]+)?#)?([a-z0-9\-\.]*)\.(([a-z]{2,4})|([0-9]{1,3}\.([0-9]{1,3})\.([0-9]{1,3})))(:[0-9]{2,5})?(\/([a-z0-9+%-]\.?)+)*\/?(\?[a-z+&$_.-][a-z0-9;:#&%=+\/.-]*)?(#[a-z_.-][a-z0-9+$%_.-]*)?/i';
// Match all
preg_match_all($re, $blob, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
// The first element of the array is the full match
This PHP Composer package URL highlight is doing a good job in PHP:
<?php
use VStelmakh\UrlHighlight\UrlHighlight;
$urlHighlight = new UrlHighlight();
$matches = $urlHighlight->getUrls($string);
?>
If it does not have to be regex, you could always use the validate filters that are in PHP.
filter_var('http://example.com', FILTER_VALIDATE_URL);
filter_var (mixed $variable [, int $filter = FILTER_DEFAULT [, mixed $options ]]);
Types of Filters
Validate Filters
Regex if you want to ensure a URL starts with HTTP/HTTPS:
https?:\/\/(www\.)?[-a-zA-Z0-9#:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()#:%_\+.~#?&//=]*)
If you do not require the HTTP protocol:
[-a-zA-Z0-9#:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()#:%_\+.~#?&//=]*)
I am looking for a way to get a valid url out of a string like:
$string = 'http://somesite.com/directory//sites/9/my_forms/3-895a3e/somefilename.jpg|:||:||:||:|19845';
My original solution was:
preg_match('#^[^:|]*#', str_replace('//', '/', $string), $modifiedPath);
But obviously its going to remove a slash from the http:// instead of the one in the middle of the string.
My expected output that I want from the original is:
http://somesite.com/directory/sites/9/my_forms/3-895a3e/somefilename.jpg
I could always break off the http part of the string first but would like a more elegant solution in the form of regex if possible. Thanks.
This will do exactly what you are asking:
<?php
$string = 'http://somesite.com/directory//sites/9/my_forms/3-895a3e/somefilename.jpg|:||:||:||:|19845';
preg_match('/^([^|]+)/', $string, $m); // get everything up to and NOT including the first pipe (|)
$string = $m[1];
$string = preg_replace('/(?<!:)\/\//', '/' ,$string); // replace all occurrences of // as long as they are not preceded by :
echo $string; // outputs: http://somesite.com/directory/sites/9/my_forms/3-895a3e/somefilename.jpg
exit;
?>
EDIT:
(?<!X) in regular expressions is the syntax for what is called a lookbehind. The X is replaced with the character(s) we are testing for.
The following expression would match every instance of double slashes (/):
\/\/
But we need to make sure that the match we are looking for is NOT preceded by the : character so we need to 'lookbehind' our match to see if the : character is there. If it is then we don't want it to be counted as a match:
(?<!:)\/\/
The ! is what says NOT to match in our lookbehind. If we changed it to (?=:)\/\/ then it would only match the double slashes that did have the : preceding them.
Here is a Quick tutorial that can explain it all better than I can lookahead and lookbehind tutorial
Assuming all your strings are in the form given, you don't need any but the simplest of regexes to do this; if you want an elegant solution, then a regex is definitely not what you need. Also, double slashes are legal in a URL, just like in a Unix path, and mean the same thing a single slash does, so you don't really need to get rid of them at all.
Why not just
$url = array_shift(preg_split('/\|/', $string));
?
If you really, really care about getting rid of the double slashes in the URL, then you can follow this with
$url = preg_replace('/([^:])\/\//', '$1/', $url);
or even combine them into
$url = preg_replace('/([^:])\/\//', '$1/', array_shift(preg_split('/\|/', $string)));
although that last form gets a little bit hairy.
Since this is a quite strictly defined situation, I'd consider just one preg to be the most elegant solution.
From the top of my head:
$sanitizedURL = preg_replace('~((?<!:)/(?=/)|\\|.+)~', '', $rawURL);
Basically, what this does is look for any forward slash that IS NOT preceded by a colon (:), and IS followed bij another forward slash. It also searches for any pipe character and any character following it.
Anything found is removed from the result.
I can explain the RegEx in more detail if you like.
I'm trying to replace:
*facebook.com/
with http://graph.facebook.com/
I need to be able to group anything before the facebook.com part into an optional group.
I can't just replace facebook.com with graph.facebook.com because the incoming URL may contain https.
Here's what I have but misses anything that doesn't have http[s]://.
<?php
$fb_url = preg_replace('/http[s]*:\/\/[www.]*facebook.com\//', 'http://graph.facebook.com/', 'facebook.com/some/segments');
echo $fb_url;
?>
Addressing your question specifically:
You can make any single character (or a group of characters) optional by adding a ? after it in your regex.
A couple of tips from looking at your code:
If you are matching strings containing / characters, simplify your life by using a different delimiter (for example #). You aren't required to use a forward slash.
You should escape the . dot metacharacter because it matches ANY single character, so your expression www. could conceivably match www9 or anything else along those lines
Also, the brackets [...] are for matching a range of characters. If you want to match specifically the text www. you should use a non-captured group like (?:www\.) and make it optional by adding the ? after it like (?:www\.)?
So, those tips in mind, try ...
<?php
$p = '#(?:https?://(?:www\.)?)?facebook\.com/#';
$r = 'http://graph.facebook.com/';
$subject = 'facebook.com/some/segments';
$fb_url = preg_replace($p, $r, $subject);
echo $fb_url; // outputs: http://graph.facebook.com/some/segments
?>
use something like below
(optional-regex-here)?