PHP regex. How to get an array of matches? - php

Question

I have a string in a format like this:
5;1-x;1-2;(1-x;)+
I used 1-x as a notation for all integers from 1 to infinity and (1-x;)+ to mark that the last integer may be repeated any number of times.
Some example strings:
5;1;1;1
5;7;2;7;5;1;9
How can I match these strings with regex and get all the (1-x;)+ matches?
I have tried the following:
preg_match_all('%5;([1-9]{1}[0-9]*);([1-2]);([1-9]{1}[0-9]*;?)+%',
$str, $matches);
And the result for string "5;1;1;1" is:
array(4) {
[0]=>
array(1) {
[0]=>
string(7) "5;1;1;1"
}
[1]=>
array(1) {
[0]=>
string(1) "1"
}
[2]=>
array(1) {
[0]=>
string(1) "1"
}
[3]=>
array(1) {
[0]=>
string(1) "1"
}
}
For the string "5;7;2;7;5;1;9" it is:
array(4) {
[0]=>
array(1) {
[0]=>
string(13) "5;7;2;7;5;1;9"
}
[1]=>
array(1) {
[0]=>
string(1) "7"
}
[2]=>
array(1) {
[0]=>
string(1) "2"
}
[3]=>
array(1) {
[0]=>
string(1) "9"
}
}
As you can see, only the last integer from (1-x;)+ is in the matches array, but I want the matches array to contain values 7, 5, 1, and 9, not just the last one. Is this even possible using regex or do I need to use another approach to validate and get values from these strings?

Answer 1

One way
//$str = "5;1;1;1";
$str = "5;7;2;7;5;1;9";
$pattern = '%^5;([1-9]\d*;)[12];((?:[1-9]\d*;?)+)$%';
$str = preg_replace( $pattern, '$1$2', $str, -1, $count );
if ( $count ) {
print_r( explode( ';', $str ) );
} else {
echo 'Invalid string';
}
The -1 means no limit to the number of replacements.
$count is the number of replacements made. It will be 1 if the string is valid, or 0 otherwise.
The above assumes a string is still valid if it ends in a ;.

Answer 2

I honestly would just explode the string and remove the unwanted first and third elements that like this:
$array = explode(';', $string);
$diff_array = array(0 => 'not_used', 2 => 'not_used');
$final_array = array_key_diff($array, $diff_array);
This gives you an array of all the values except the first and third elements which are the ones which you seem to not be interested in.
If you then need to verify that the remaining elements are indeed integers with value >= 1 you could run an array_filter on it like this:
$filtered_array = array_filter($final_array, function($value) {
if ((string)(int)$value == $value && (int)$value >= 1) return true;
return false;
}