php array multi-dimensional indexing

Question

I am pretty green when it comes to php, so here's a basic question for which I have not found an answer yet.

I extract repetitive information from a page by doing regex matching as follows. The regex has two capturing groups (...), hence the $matches array has index ranging from 0 (full regex value) to 2 ( 1 and 2 are the capturing group values).

<?php
    $page = file_get_contents(url);
    preg_match_all(regex-with-two-capturing-groups, $page, $matches);
    $m1 = $matches[1];
    $m2 = $matches[2];
    for ($i=0; $i < sizeof($m1); $i++) {
        echo ("<tr><td>$m1[$i]</td><td>$m2[$i]</td></tr>");
    }
?>

This works fine, but at first I tried a shorter version:

<?php
    $page = file_get_contents(url);
    preg_match_all(regex-with-two-capturing-groups, $page, $matches);
    for ($i=0; $i < sizeof($matches[0]); $i++) {
        echo ("<tr><td>$matches[1][$i]</td><td>$matches[2][$i]</td></tr>");
    }
?>

but this resulted in

<tr><td>Array[0]</td><td>Array[0]</td></tr>
<tr><td>Array[1]</td><td>Array[1]</td></tr>
<tr><td>Array[2]</td><td>Array[2]</td></tr>
<tr><td>Array[3]</td><td>Array[3]</td></tr>
<tr><td>Array[4]</td><td>Array[4]</td></tr>
...

Why is this?
And is there a way to do two-dimensional indexing in one expression, not having to define intermediate arrays m1 and m2?

Community · Accepted Answer · 2017-05-23 12:29:10Z

2

Use this code:

<?php
    $page = file_get_contents(url);
    preg_match_all(regex-with-two-capturing-groups, $page, $matches);
    for ($i=0; $i < sizeof($matches[0]); $i++) {
        echo ("<tr><td>".$matches[1][$i]."</td><td>".$matches[2][$i]."</td></tr>");
    }
?>

PHP Documentation : language.types.string.parsing

Look also here : PHP: concatenation of multidimensional array elements

edited May 23, 2017 at 12:29

CommunityBot

11 silver badge

answered Jun 11, 2012 at 12:06

rkosegi

14.8k5 gold badges57 silver badges90 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Maestro13 Over a year ago

All right, so . (dot) is sort of a string concatenate operator?

rkosegi Over a year ago

@Maestro13 : Maybe because of multi-dimensional array qualifier.Always use . as concatenation, it increase readability of your code and prevents you from solving such issues.See my updated answer.

Collectives™ on Stack Overflow

php array multi-dimensional indexing

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related