Trying to replace all occurrences of an #mention with an anchor tag, so far I have:
$comment = preg_replace('/#([^# ])? /', '#$1 ', $comment);
Take the following sample string:
"#name kdfjd fkjd as#name # lkjlkj #name"
Everything matches okay so far, but I want to ignore that single "#" symbol. I've tried using "+" and "{2,}" after the "[^# ]" which I thought would enforce a minimum amount of matches, but it's not working.
Replace the question mark (?) quantifier ("optional") and add in a + ("one or more") after your character class:
#([^# ]+)
The regex
(^|\s)(#\w+)
Might be what you are after.
It basically means, the start of the line, or a space, then an # symbol followed by 1 or more word characters.
E.g.
preg_match_all('/(^|\s)(#\w+)/', '#name1 kdfjd fkjd as#name2 # lkjlkj #name3', $result);
var_dump($result[2]);
Gives you
Array
(
[0] => #name1
[1] => #name3
)
I like Petah's answer but I adjusted it slightly
preg_replace('/(^|\s)#([\w.]+)/', '$1#$2', $text);
The main differences are:
the # symbol is not included. That's for display only, should not be in the URL
allows . character (note: \w includes underscore)
in the replacement, I added $1 at the beginning to preserve the whitespace
Replacing ? with + will work but not as you expect.
Your expression does not match #name at the end of string.
$comment = preg_replace('##(\w+)#', '$0 ', $comment);
This should do what you want. \w+ stands for letter (a-zA-Z0-9)
I recommend using a lookbehind before matching the # then one or more characters which are not a space or #.
The "one or more" quantifier (+) prevents the matching of mentions that mention no one.
Using a lookbehind is a good idea because it not only prevents the matching of email addresses and other such unwanted substrings, it asks the regex engine to primarily search #s then check the preceding character. This should improve pattern performance since the number of spaces should consistently outnumber the number of mentions in comments.
If the input text is multiline or may contain newlines, then adding an m pattern modifier will tell ^ to match all line starts. If newlines and tabs are possible, is will be more reliable to use (?<=^|\s)#([^#\s]+).
Code: (Demo)
$comment = "#name kdfjd ## fkjd as#name # lkjlkj #name";
var_export(
preg_replace(
'/(?<=^| )#([^# ]+)/',
'#$1',
$comment
)
);
Output: (single-quotes are from var_export())
'#name kdfjd ## fkjd as#name # lkjlkj #name'
Try:
'/#(\w+)/i'
Related
I have 2 texts in a string:
%Juan%
%Juan Gonzalez%
And I want to only be able to get %Juan% and not the one with the Space, I have been trying several Regexes witout luck. I currently use:
/%(.*)%/U
but it gets both things, I tried adding and playing with [^\s] but it doesnt works.
Any help please?
The issue is that . matches any character but a newline. The /U ungreedy mode only makes .* lazy and it captures a text from the % up to the first % to the right of the first %.
If your strings contain one pair of %...%, you may use
/%(\S+)%/
See the regex demo
The \S+ pattern matches 1+ characters other than a whitespace, and the whole [^\h%] negated character class that matches any character but a horizontal space and % symbol.
If you have multiple %...% pairs, you may use
/%([^\h%]+)%/
See another regex demo, where \h matches any horizontal whitespace.
PHP demo:
$re = '/%([^\h%]+)%/';
$str = "%Juan%\n%Juan Gonzalez%";
preg_match_all($re, $str, $matches);
print_r($matches[1]);
I need a Regular Expression to remove ALL single characters from a string, not just single letters or numbers
The string is:
"A Future Ft Casino Karate Chop ( Prod By Metro )"
it should come out as:
"Future Ft Casino Karate Chop Prod By Metro"
The expression I am using at the moment (in PHP), correctly removes the single 'A' but leaves the single '(' and ')'
This is the code I am using:
$string = preg_replace('/\b\w\b\s?/', '', $string);
Try this:
(^| ).( |$)
Breakdown:
1. (^| ) -> Beginning of line or space
2. . -> Any character
3. ( |$) -> Space or End of line
Actual code:
$string = preg_replace('/(^| ).( |$)/', '$1', $string);
Note: I'm not familiar with the workings of PHP regex, so the code might need a slight tweak depending on how the actual regex needs declared.
As m.buettner pointed out, there will be a trailing white space here with this code. A trim would be needed to clear it out.
Edit: Arnis Juraga pointed out that this would not clear out multiple single characters a b c would filter out to b. If this is an issues use this regex:
(^| ).(( ).)*( |$)
The (( ).)* added to the middle will look for any space following by any character 0 or more times. The downside is this will end up with double spaces where a series of single characters were located.
Meaning this:
The a b c dog
Will become this:
The dog
After performing the replacement to get single individual characters, you would need to use the following regex to locate the double spaces, then replace with a single space
( ){2}
A slightly more efficient version that does not require capturing would be using lookarounds. It's a bit less intuitive due to the multiple negative logic:
$string = preg_replace('/(?<!\S).(?!\S)\s*/', '', $input);
This will remove any character that is neither preceded nor followed by a non-whitespace character (so only those that are between whitespace or at the string boundaries). It will also include all trailing whitespace in the match, so as to leave only the preceding whitespace if there is any. The caveat is, that just like Nick's answer the ) at the end of the string will leave a trailing whitespace (because it is in front of the character). This can easily be solved by trimming the string.
I am working on a script that develops certain strings of alphanumeric characters, separated by a dash -. I need to test the string to see if there are any sets of characters (the characters that lie in between the dashes) that are the same. If they are, I need to consolidate them. The repeating chars would always occur at the front in my case.
Examples:
KRS-KRS-454-L
would become:
KRS-454-L
DERP-DERP-545-P
would become:
DERP-545-P
<?php
$s = 'KRS-KRS-454-L';
echo preg_replace('/^(\w+)-(?=\1)/', '', $s);
?>
// KRS-454-L
This uses a positive lookahead (?=...) to check for repeated strings.
Note that \w also contains the underscore. If you want to limit to alphanumeric characters only, use [a-zA-Z0-9].
Also, I've anchored with ^ as you've mentioned: "The repeating chars would always occur at the front [...]"
Try the pattern:
/([a-z]+)(?:-\1)*(.*)/i
and replace it with:
$1$2
A demo:
$tests = array(
'KRS-KRS-454-L',
'DERP-DERP-DERP-545-P',
'OKAY-666-A'
);
foreach ($tests as $t) {
echo preg_replace('/([a-z]+)(?:-\1)*(.*)/i', '$1$2', $t) . "\n";
}
produces:
KRS-454-L
DERP-545-P
OKAY-666-A
A quick explanation:
([a-z]+) # group the first "word" in match group 1
(?:-\1)* # match a hyphen followed by what was matched in
# group 1, and repeat it zero or more times
(.*) # match the rest of the input and store it in group 2
the replacement string $1$2 are replaced by what was matched by group 1 and group 2 in the pattern above.
Use this regex ((?:[A-Z-])+)\1{1} and replaced the matched string by $1.
\1 is used in connection with {1} in the above regex. It will look for repeating instance of characters.
You need back references. Using perl syntax, this would work for you:
$line =~ s/([A-Za-z0-9]+-)\1+/\1/gi;
How would I go about removing numbers and a space from the start of a string?
For example, from '13 Adam Court, Cannock' remove '13 '
Because everyone else is going the \d+\s route I'll give you the brain-dead answer
$str = preg_replace("#([0-9]+ )#","",$str);
Word to the wise, don't use / as your delimiter in regex, you will experience the dreaded leaning-toothpick-problem when trying to do file paths or something like http://
:)
Use the same regex I gave in my JavaScript answer, but apply it using preg_replace():
preg_replace('/^\d+\s+/', '', $str);
Try this one :
^\d+ (.*)$
Like this :
preg_replace ("^\d+ (.*)$", "$1" , $string);
Resources :
preg_replace
regular-expressions.info
On the same topic :
Regular expression to remove number, then a space?
regular expression for matching number and spaces.
I'd use
/^\d+\s+/
It looks for a number of any size in the beginning of a string ^\d+
Then looks for a patch of whitespace after it \s+
When you use a backslash before certain letters it represents something...
\d represents a digit 0,1,2,3,4,5,6,7,8,9.
\s represents a space .
Add a plus sign (+) to the end and you can have...
\d+ a series of digits (number)
\s+ multiple spaces (typos etc.)
The same regex I gave you on your other question still applies. You just have to use preg_replace() instead.
Search for /^[\s\d]+/ and replace with the empty string. Eg:
$str = preg_replace(/^[\s\d]+/, '', $str);
This will remove digits and spaces in any order from the beginning of the string. For something that removes only a number followed by spaces, see BoltClock's answer.
If the input strings all have the same ecpected format and you will receive the same result from left trimming all numbers and spaces (no matter the order of their occurrence at the front of the string), then you don't actually need to fire up the regex engine.
I love regex, but know not to use it unless it provides a valuable advantage over a non-regex technique. Regex is often slower than non-regex techniques.
Use ltrim() with a character mask that includes spaces and digits.
Code: (Demo)
var_export(
ltrim('420 911 90210 666 keep this part', ' 0..9')
);
Output:
'keep this part'
It wouldn't matter if the string started with a space either. ltrim() will greedily remove all instances of spaces or numbers from the start of the string intil it can't anymore.
How can I match a space character in a PHP regular expression?
I mean like "gavin schulz", the space in between the two words. I am using a regular expression to make sure that I only allow letters, number and a space. But I'm not sure how to find the space. This is what I have right now:
$newtag = preg_replace("/[^a-zA-Z0-9s|]/", "", $tag);
If you're looking for a space, that would be " " (one space).
If you're looking for one or more, it's " *" (that's two spaces and an asterisk) or " +" (one space and a plus).
If you're looking for common spacing, use "[ X]" or "[ X][ X]*" or "[ X]+" where X is the physical tab character (and each is preceded by a single space in all those examples).
These will work in every* regex engine I've ever seen (some of which don't even have the one-or-more "+" character, ugh).
If you know you'll be using one of the more modern regex engines, "\s" and its variations are the way to go. In addition, I believe word boundaries match start and end of lines as well, important when you're looking for words that may appear without preceding or following spaces.
For PHP specifically, this page may help.
From your edit, it appears you want to remove all non valid characters The start of this is (note the space inside the regex):
$newtag = preg_replace ("/[^a-zA-Z0-9 ]/", "", $tag);
# ^ space here
If you also want trickery to ensure there's only one space between each word and none at the start or end, that's a little more complicated (and probably another question) but the basic idea would be:
$newtag = preg_replace ("/ +/", " ", $tag); # convert all multispaces to space
$newtag = preg_replace ("/^ /", "", $tag); # remove space from start
$newtag = preg_replace ("/ $/", "", $tag); # and end
Cheat Sheet
Here is a small cheat sheet of everything you need to know about whitespace in regular expressions:
[[:blank:]]
Space or tab only, not newline characters. It is the same as writing [ \t].
[[:space:]] & \s
[[:space:]] and \s are the same. They will both match any whitespace character spaces, newlines, tabs, etc...
\v
Matches vertical Unicode whitespace.
\h
Matches horizontal whitespace, including Unicode characters. It will also match spaces, tabs, non-breaking/mathematical/ideographic spaces.
x (eXtended flag)
Ignore all whitespace. Keep in mind that this is a flag, so you will add it to the end of the regex
like /hello/gmx. This flag will ignore whitespace in your regular expression.
For example, if you write an expression like /hello world/x, it will match helloworld, but not hello world. The extended flag also allows comments in your regex.
Example
/helloworld #hello this is a comment/
If you need to use a space, you can use \ to match spaces.
To match exactly the space character, you can use the octal value \040 (Unicode characters displayed as octal) or the hexadecimal value \x20 (Unicode characters displayed as hex).
Here is the regex syntax reference: https://www.regular-expressions.info/nonprint.html.
In Perl the switch is \s (whitespace).
I am using a regex to make sure that I
only allow letters, number and a space
Then it is as simple as adding a space to what you've already got:
$newtag = preg_replace("/[^a-zA-Z0-9 ]/", "", $tag);
(note, I removed the s| which seemed unintentional? Certainly the s was redundant; you can restore the | if you need it)
If you specifically want *a* space, as in only a single one, you will need a more complex expression than this, and might want to consider a separate non-regex piece of logic.
It seems to me like using a REGEX in this case would just be overkill. Why not just just strpos to find the space character. Also, there's nothing special about the space character in regular expressions, you should be able to search for it the same as you would search for any other character. That is, unless you disabled pattern whitespace, which would hardly be necessary in this case.
You can also use the \b for a word boundary. For the name I would use something like this:
[^\b]+\b[^\b]+(\b|$)
EDIT Modifying this to be a regex in Perl example
if( $fullname =~ /([^\b]+)\b[^\b]+([^\b]+)(\b|$)/ ) {
$first_name = $1;
$last_name = $2;
}
EDIT AGAIN Based on what you want:
$new_tag = preg_replace("/[\s\t]/","",$tag);
Use it like this to allow for a single space.
$newtag = preg_replace("/[^a-zA-Z0-9\s]/", "", $tag)
I'm trying out [[:space:]] in an instance where it looks like bloggers in WordPress are using non-standard space characters. It looks like it will work.
This matches tires better because not all vendors use the same size format. I deal with many vendors all doing size in different format. This is my expression for now
/^[\d][\d](?:\d)?(?:\-|\/|\s)?([?:\d]+)?(?:\.)?(?:\d)?(?:\d)?(?:R|-|\s)?[1-3]([?:[\d]+)?(?:\.)?([?:\d])?(?:\s|-)/img
will catch all
35-12.50-22 HAIDA[AA]
35-12-22 HAIDA[AA]
35/35R20
35/35r20
thus uis a test
rrrrr
awdg
3345588
225-45-17 ACCELERA[AC]
195 50 16 KELLY
1955016 KELLY
CP671"
158 Buckshot
165-40-16-ACHILLES
11-24.5-16-LEAO-LLA08
11-24.5-LEAO-D37
11-22.5-14-LINGLONG-LLD37
11-22.5-HAPPYROAD[AA]