I am trying to use preg_match to find a certain word in a string of text.
$pattern = "/" . $myword . "/i";
This pattern will find the word "car" inside "cartoon"...
I need just matches where the certain word appears.
P.S The word may be anywhere inside the text.
Thanks
Wrap your regex with word-boundaries:
$pattern = "/\b" . $myword . "\b/i";
or, if your $myword may contain regex-meta-chars, do:
$pattern = "/\b" . preg_quote($myword) . "\b/i";
Try this:
$pattern = "/\b" . $myword . "\b/i";
In regular expressions, the \b escape character represents a "word boundary" character. By wrapping your search term within these boundary matches, you ensure that you will only match the word itself.
$subject = "abcdef";
$pattern = '/^def/';
preg_match($pattern, $subject, $matches, PREenter code hereG_OFFSET_CAPTURE, 3);
print_r($matches);
pattern
The pattern to search for, as a string.
subject
The input string.
matches
If matches is provided, then it is filled with the results of search. $matches[0] will contain the text that matched the full pattern, $matches[1] will have the text that matched the first captured parenthesized subpattern, and so on.
flags
flags can be the following flag:
PREG_OFFSET_CAPTURE
If this flag is passed, for every occurring match the appendant string offset will also be returned. Note that this changes the value of matches into an array where every element is an array consisting of the matched string at offset 0 and its string offset into subject at offset 1.
offset
Normally, the search starts from the beginning of the subject string. The optional parameter offset can be used to specify the alternate place from which to start the search (in bytes).
Example:
if (preg_match('/;/', $_POST['value_code']))
{
$input_error = 1;
display_error(_("The semicolon can not be used in the value code."));
set_focus('value_code');
}
Related
I have a string like "some words 12345cm some more words"
and I want to extract the 12345cm bit from that string. So I get the position of the first number:
$position_of_first_number = strcspn( "some words 12345cm some more words" , '0123456789' );
Then the position of the first space after $position_of_first_number
$position_of_space_after_numbers = strpos("some words 12345cm some more words", " ", $position_of_first_number);
Then I want to have a function which return the portion of the string between $position_of_first_number and $position_of_space_after_numbers.
How do I do it?
You can use the substr function. Note that it takes a starting position and a length, which you can calculate as the difference between the start and end positions.
Since you are looking for a pattern like blank-digits-letters-blank, I would recommend a regular expression using preg_match:
$s = "some words 12345cm some more words";
preg_match("/\s(?P<result>\d+[^\W\d_]+)\s/", $s, $matches);
echo $matches["result"];
12345cm
Explaining the pattern:
"/.../" limits the pattern in PHP
\s matches any whitespace character
(?P<name>...) names the following pattern
\d+ matches 1 or more digits
[^\W\d_]+ matches 1 or more Unicode-letters (i.e. any character that is not a non-alphanumeric character; see this answer)
I am trying to replace 2.0 to stack,
but the following code replace 2008 to 2.08
Following is my code:
$string = 'The story is inspired by the Operation Batla House that took place in 2008 ';
$tag = '2.0';
$pattern = '/(\s|^)'.($tag).'(?=[^a-z^A-Z])/i';
echo preg_replace($pattern, '2.0', $string);
Use preg_quote and make sure you pass the regex delimiter as the second argument:
$string = 'The story is inspired by the Operation Batla House that took place in 2008 ';
$tag = '2.0';
$pattern = '/(\s|^)' . preg_quote($tag, '/') . '(?=[^a-zA-Z])/i';
// ^^^^^^^^^^^^^^^^^^^^^
echo preg_replace($pattern, '2.0', $string);
The string is not modified. See the PHP demo. The regex delimiter here is /, thus it is passed as the 2nd parameter to preg_quote.
Note that [^a-z^A-Z] matches any chars but ASCII letters and ^ since you added the second ^ in the character class. I changed [^a-z^A-Z] to [^a-zA-Z].
Also, the capturing group at the start may be replaced with a single lookbehind, (?<!\S), it will make sure your match occurs only at the string start or after a whitespace.
If you expect to also match at the end of the string, replace (?=[^a-zA-Z]) (that requires a char other than a letter immediately to the right of the current location) with (?![a-zA-Z]) (that requires a char other than a letter or end of string immediately to the right of the current location).
So, use
$pattern = '/(?<!\S)' . preg_quote($tag, '/') . '(?![a-zA-Z])/i';
Also, consider using unambiguous word boundaries
$pattern = '/(?<!\w)' . preg_quote($tag, '/') . '(?!\w)/i';
Considering this input string:
"this is a Test String to get the last index of word with an uppercase letter in PHP"
How can I get the position of the last uppercase letter (in this example the position of the first "P" (not the last one "P") of "PHP" word?
I think this regex works. Give it a try.
https://regex101.com/r/KkJeho/1
$pattern = "/.*\s([A-Z])/";
//$pattern = "/.*\s([A-Z])[A-Z]+/"; pattern to match only all caps word
Edit to solve what Wiktor wrote in comments I think you could str_replace all new lines with space as the input string in the regex.
That should make the regex treat it as a single line regex and still give the correct output.
Not tested though.
To find the position of the letter/word:
$str = "this is a Test String to get the last index of word with an uppercase letter in PHP";
$pattern = "/.*\s([A-Z])(\w+)/";
//$pattern = "/.*\s([A-Z])([A-Z]+)/"; pattern to match only all caps word
preg_match($pattern, $str, $match);
$letter = $match[1];
$word = $match[1] . $match[2];
$position = strrpos($str, $match[1].$match[2]);
echo "Letter to find: " . $letter . "\nWord to find: " . $word . "\nPosition of letter: " . $position;
https://3v4l.org/sJilv
If you also want to consider a non-regex version: You can try splitting the string at the whitespace character, iterating the resulting string array backwards and checking if the current string's first character is an upper case character, something like this (you may want to add index/null checks):
<?php
$str = "this is a Test String to get the last index of word with an uppercase letter in PHP";
$explodeStr = explode(" ",$str);
$i = count($explodeStr) - 1;
$characterCount=0;
while($i >= 0) {
$firstChar = $explodeStr[$i][0];
if($firstChar == strtoupper($firstChar)){
echo $explodeStr[$i]. ' at index: ';
$idx = strlen($str)-strlen($explodeStr[$i] -$characterCount);
echo $idx;
break;
}
$characterCount += strlen($explodeStr[i]) +1; //+1 for whitespace
$i--;
}
This prints 80 which is indeed the index of the first P in PHP (including whitespaces).
Andreas' pattern looks pretty solid, but this will find the position faster...
.* \K[A-Z]{2,}
Pattern Demo
Here is the PHP implementation: Demo
$str='this is a Test String to get the last index of word with an uppercase letter in PHP test';
var_export(preg_match('/.* \K[A-Z]{2,}/',$str,$out,PREG_OFFSET_CAPTURE)?$out[0][1]:'fail');
// 80
If you want to see a condensed non-regex method, this will work:
Code: Demo
$str='this is a Test String to get the last index of word with an uppercase letter in PHP test';
$allcaps=array_filter(explode(' ',$str),'ctype_upper');
echo "Position = ",strrpos($str,end($allcaps));
Output:
Position = 80
This assumes that there is an all caps word in the input string. If there is a possibility of no all-caps words, then a conditional would sort it out.
Edit, after re-reading the question, I am unsure what exactly makes PHP the targeted substring -- whether it is because it is all caps, or just the last word to start with a capitalized letter.
If just the last word starting with an uppercase letter then this pattern will do: /.* \K[A-Z]/
If the word needs to be all caps, then it is possible that /b word boundaries may be necessary.
Some more samples and explanation from the OP would be useful.
Another edit, you can declare a set of characters to exclude and use just two string functions. I am using a-z and a space with rtrim() then finding the right-most space, and adding 1 to it.
$str='this is a Test String to get the last index of word with an uppercase letter in PHP test';
echo strrpos(rtrim($str,'abcdefghijklmnopqrstuvwxyz '),' ')+1;
// 80
How can I check if a string has the format [group|any_title] and give me the title back?
[group|This is] -> This is
[group|just an] -> just an
[group|example] -> example
I would do that with explode and [group| as the delimiter and remove the last ]. If length (of explode) is > 0, then the string has the correct format.
But I think that is not quite a good way, isn't it?
So you want to check if a string matches a regex?
if(preg_match('/^\[group\|(.+)\]$/', $string, $m)) {
$title = $m[1];
}
If the group part is supposed to be dynamic as well:
if(preg_match('/^\[(.+)\|(.+)\]$/', $string, $m)) {
$group = $m[1];
$title = $m[2];
}
Use regular expression matching using PHP function preg_match.
You can use for example regexr.com to create and test a regular expression and when you're done, then implement it in your PHP script (replace the first parameter of preg_match with your regular expression):
$text = '[group|This is]';
// replace "pattern" with regular expression pattern
if (preg_match('/pattern/', $text, $matches)) {
// OK, you have parts of $text in $matches array
}
else {
// $text doesn't contain text in expected format
}
Specific regular expression pattern depends on how strictly you want to check your input string. It can be for example something like /^\[.+\|(.+)\]$/ or /\|([A-Za-z ]+)\]$/. First checks if string starts with [, ends with ] and contains any characters delimited by | in between. Second one just checks if string ends with | followed by upper and lower case alphabetic characters and spaces and finally ].
I am trying to make sense of handling regular expression with php. So far my code is:
PHP code:
$string = "This is a 1 2 3 test.";
$pattern = '/^[a-zA-Z0-9\. ]$/';
$match = preg_match($pattern, $string);
echo "string: " . $string . " regex response: " , $match;
Why is $match always returning 0 when I think it should be returning a 1?
[a-zA-Z0-9\. ] means one character which is alphanumeric or "." or " ". You will want to repeat this pattern:
$pattern = '/^[a-zA-Z0-9. ]+$/';
^
"one or more"
Note: you don't need to escape . inside a character group.
Here's what you're pattern is saying:
'/: Start the expressions
^: Beginning of the string
[a-zA-Z0-9\. ]: Any one alphanumeric character, period or space (you should actually be using \s for spaces if your intention is to match any whitespace character).
$: End of the string
/': End the expression
So, an example of a string that would yield a match result is:
$string = 'a'
Of other note, if you're actually trying to get the matches from the result, you'll want to use the third parameter of preg_match:
$numResults = preg_match($pattern, $string, $matches);
You need a quantifier on the end of your character class, such as +, which means match 1 or more times.
Ideone.