I have a preg match statement, and it checks for matches, but I was wondering how you can count the matches. Any advice appreciated.
$message='[tag] [tag]';
preg_match('/\[tag]\b/i',$message);
for example a count of this message string should lead to 2 matches
$message='[tag] [tag]';
echo preg_match_all('/\\[tag\\](?>\\s|$)/i', $message, $matches);
gives 2. Note you cannot use \b because the word boundary is before the ], not after.
See preg_match_all.
preg_match already returns the number of times the pattern matched.
However, this will only be 0 or 1 as it stops after the first match. You can use preg_match_all instead as it will check the entire string and return the total number of matches.
You should use preg_match_all if you want to match all occurences. preg_match_all returns number of matches. preg_match returns only 0 or 1, because it matches only once.
I think you need preg_match_all. It returns the number of matches it finds. preg_match stops after the first one.
You could use T-Regx library with count() method (and even automatic delimiters):
$count = pattern('\[tag]\b', 'i')->match('[tag] [tag]')->count();
$count // 2
Related
I cant remember what to use to return only a specific part of a string.
I have a string like this:-
$str = "return(me or not?)";
I want to get the word which is after (. In this example me will be my result. How can I do this?
I dont think substr is what I am looking for. as substr returns value based on the index you provided. which in this case i dont know the index, it can vary. All I know is that I want to return whatever is after "(" and before the space " ". The index positions will always be different there for i cant use substr(..).
This regular expression should do the trick. Since you didn't provide general rules but only an example it might need further changes though.
preg_match('/\((\S+)/', $input, $matches);
$matches[1] contains "me" then.
<?php
// Your input string
$string = "return(me or not?)";
// Pattern explanation:
// \( -- Match opening parentheses
// ([^\s]+) -- Capture at least one character that is not whitespace.
if (preg_match('/\(([^\s]+)/', $string, $matches) === 1)
// preg_match() returns 1 on success.
echo "Substring: {$matches[1]}";
else
// No match found, or bad regular expression.
echo 'No match found';
Result of capture group will be your result using this regex and preg_match().
$regex = '/\((\w+)/';
Check preg_match() for the working reference.
i want to preg_match following as it is
$this_string = '{95}1340{113}1488{116}1545{99}1364';
My best try was
preg_match('/^[\{\d+\}\d+]+$/', $this_string);
That matches
{95}1340{113}1488
but also
{95}1340{113}
which is wrong.
I know why it is matching last example. One match {95}1340 was true, so '+' 'll be always true. But i don't know how to tell, if it match, so it has always be a complete match in '[…]'
i do expect only matches likes these
{…}…
{…}…{…}…
{…}…{…}…{…}…
one of the tries:
^(\{\d+\}\d+)+$
does also match
{99}1364
at the very last end of this string as a second match, so i get back an Array with two Elements:
Array[0] = {95}1340{113}1488{116}1545{99}1364 and
Array[1] = {99}1364
Problem is unnecessary use of character class in your regex i.e. [ and ].
You can use:
'/^(\{\d+\}\d+)+$/'
The translation of your regex to a clearer thing would be: /^[\{\}0-9+]+$/, this would be explained as everything that is inside this chracters {}0123456789+, exactly those ones.
What you want is grouping, for grouping, parentheses are needed and not character classes () instead [], so what you want to do is replace [] for ().
Short answer: '/^(\{\d+\}\d+)+$/'
What you are trying to do is a little unclear. Since your last edit, I assume that you want to check the global format of the string and to extract all items (i.e. {121}1231) one by one. To do that you can use this code:
$str = '{95}1340{113}1488{116}1545{99}1364';
$pattern = '~\G(?:{\d+}\d+|\z)~';
if (preg_match_all($pattern, $str, $matches) && empty(array_pop($matches[0])))
print_r($matches[0]);
\G is an anchor for the start of the string or the end of the previous match
\z is an anchor for the end of the string
The alternation with \z is only needed to check that the last match is at the end of the string. If the last match is empty, you are sure that the format is correct until the end.
how would I avoid that the following :
$_SESSION['myVar']=preg_match("[^a-zA-Z]",'',$_SESSION['myVar']);
echo $_SESSION['myVar'];
displays
0
and instead it displays/outputs the var content ? preg_match gives out mixed type, but this shouldnt be the problem...
Why, is the value of the string itself not addressable with echo (by comapring its contents, it is OK)?
Formerly I had
$_SESSION['myVar']=ereg_replace("[^a-zA-Z]",'',$_SESSION['myVar']);
ant the output óf ereg_replace was correctly displayed the variable content.
PCRE in PHP need delimiters [docs] and you probably want preg_replace [docs]:
preg_replace("/[^a-zA-Z]/",'',$_SESSION['myVar']);
Assuming you had preg_replace, even then, the brackets ([...]) would be interpreted as delimiters and so the engine would literally try to match a-zA-Z at the beginning of the string and would not interpret the constructor as character class.
preg_match returns an int, not mixed: http://php.net/manual/en/function.preg-match.php
Use the matches parameter to get your matches.
The problem is that preg_match returns a Boolean, 1 if the pattern was matched, 0 if it didn't. preg_match simply matches occurrences, it doesn't replace them. Here's how you use preg_match:
$matched = array();
preg_match("/[^a-zA-Z]/", $_SESSION["myVar"], $matches);
print_r($matches); // All matches are in the array.
I want to find the first matching string in a very very long text. I know I can use preg_grep() and take the first element of the returned array. But it is not efficient to do it like that if I only need the first match (or I know there is exactly only one match in advance). Any suggestion?
preg_match() ?
preg_match() returns the number of
times pattern matches. That will be
either 0 times (no match) or 1 time
because preg_match() will stop
searching after the first match.
preg_match_all() on the contrary will
continue until it reaches the end of
subject. preg_match() returns FALSE if
an error occurred.
Here's an example of how you can do it:
$string = 'A01B1/00asdqwe';
$pattern = '~^[A-Z][0-9][0-9][A-Z][0-9]+~';
if (preg_match($pattern, $string, $match) ) {
echo "We have matched: $match[0]\n";
} else {
echo "Not matched\n";
}
You can try print_r($match) to check the array structure and test your regex.
Side note on regex:
The tilde ~ in the regex are just delimiters needed to wrap around
the pattern.
The caret ^ denote that we are matching from the start
of the string (optional)
The plus + denotes that we can have one or
more integers that follow. (So that A01B1, A01B12, A01B123 will also
be matched.
Okay, I am a noob to regex, and I am using this site for my regex primer:
Question: using the s modifier, the code below is suppose to echo 4 as it has found 4 newline characters.
However, when I run this I get one(1), why?
link text
<?php
/*** create a string with new line characters ***/
$string = 'sex'."\n".'at'."\n".'noon'."\n".'taxes'."\n";
/*** look for a match using s modifier ***/
echo preg_match("/sex.at.noon/s", $string, $matches);
/*The above code will echo 4 as it has found 4 newline characters.*/
?>
Use preg_match_all() instead which doesn't stop after the first match.
preg_match() returns the number of times pattern matches. That will be either 0 times (no match) or 1 time because preg_match() will stop searching after the first match. preg_match_all() on the contrary will continue until it reaches the end of subject . preg_match() returns FALSE if an error occurred. —PHP.net
However, the code will output still only 1 because what you are matching is the regex "sex.at.noon" and not a line break.
preg_match() will only ever return 0 or 1 because it stops after the first time the pattern matches. If you use preg_match_all() it will still return 1 because your pattern only matches once in the string you're matching against.
If you want the number of newlines via regex:
echo preg_match_all("/\n/m", $string, $matches);
Or via string functions:
echo substr_count($string, "\n");