Retrieving Values from an Array in PHP - php

Question

If you make an array and fill it with values with the function preg_match_all , how do you retrieve each separate value from the array (basically scan through it from index 0 to length)? I want to take each value and perform another function on it, so how would I return each value stored in the array? (I want arr's value at index 0, at index 1, etc.)
$contents = file_get_contents('words.txt');
$arr = array();
preg_match_all($pattern, $contents, $arr); //finds all matches
$curr = current($arr);
I tried doing this (my pattern was written elsewhere) and echoing it afterwards, but I keep getting the string "Array".

Answer 1

$contents=file_get_contents('words.txt');
$arr=array();
preg_match_all($pattern,$contents,$arr);//finds all matches
foreach ($arr as $item) {
$curr=current($arr);
// do something
}

Answer 2

preg_match_all() takes at least Parameters: (1) The Regex. (2) The String to Match your Regex against. It also takes a third Optional Parameter which gets automatically populated with all the found matches. This 3rd Argument is a Numerically indexed Array. Thus you can loop through it like like you would a Normal Array as well as treat it like any normal Array (which it is). The Snippet below demonstrate this using your Code:
<?php
$contents = file_get_contents('words.txt');
//$arr = array(); //<== NO NEED TO PRE-DECLARE THIS HERE
preg_match_all($pattern, $contents, $arr);//finds all matches
// IF YOU JUST WANT THE 1ST (CURRENT MATCH), SIMPLY USE current:
$curr = current($arr);
// YOU MAY KEEP MOVING THE CURSOR TO THE NEXT ITEM LIKE SO:
$next1 = next($arr);
$next2 = next($arr);
// OR JUST LOOP THROUGH THE FOUND MATCHES: $arr
foreach($arr as $match){
$curr = current($arr); //<== BUT THIS IS SOMEWHAT REDUNDANT WITHIN THIS LOOP.
// THE VARIABLE $match CONTAINS THE MATCHED STRING WITHIN THE CURRENT ITERATION:
var_dump($match); //<== RETURNS THE CURRENT VALUE WITHIN ITERATION
}
// YOU MAY EVEN USE NUMERIC INDEXES TO ACCESS THEM LIKE SO.
$arrLen = count($arr);
$elem0 = isset($arr[0])?$arr[0]:null;
$elem1 = isset($arr[1])?$arr[1]:null;
$elem2 = isset($arr[2])?$arr[2]:null;
$elem3 = isset($arr[3])?$arr[3]:null; //<== AND SO ON...

Answer 3

If I understand well your question, you want to know how looks the results stored in the third parameter of preg_match_all.
preg_match_all stores the results in the third parameter as a 2-dimensional array.
Two structures are possible and can be explicitly set with two constants in the fourth parameter.
Let's say you have a pattern with two capture groups and your subject string contains 3 occurrences of your pattern:
1) PREG_PATTERN_ORDER is the default setting that returns something like that:
[
0 => [ 0 => 'whole match 1',
1 => 'whole match 2',
2 => 'whole match 3' ],
1 => [ 0 => 'capture group 1 from match 1',
1 => 'capture group 1 from match 2',
2 => 'capture group 1 from match 3' ],
2 => [ 0 => 'capture group 2 from match 1',
1 => 'capture group 2 from match 2',
2 => 'capture group 2 from match 3' ]
]
2) PREG_SET_ORDER that returns something like that:
[
0 => [ 0 => 'whole match 1',
1 => 'capture group 1 from match 1',
2 => 'capture group 2 from match 1' ],
1 => [ 0 => 'whole match 2',
1 => 'capture group 1 from match 2',
2 => 'capture group 2 from match 2' ],
2 => [ 0 => 'whole match 3',
1 => 'capture group 1 from match 3',
2 => 'capture group 2 from match 3' ]
]
Concrete examples can be found in the PHP manual. You only need to choose which is the more convenient option for what you need to do.
So, to apply your function, all you need to do is to perform a foreach loop or to use array_map (that is a hidden loop too, but shorter and slower).
In general, if you aren't sure what is the structure of a variable, you can use print_r or var_dump to know how it looks like.