PHP Find all occurrences of a substring in a string

Question

I need to parse an HTML document and to find all occurrences of string asdf in it.

I currently have the HTML loaded into a string variable. I would just

Answer 1

<?php
$mainString = "ffffdjmnpfffffdjmnpffff";
$needle = "jmnp";
$lastPos = 0;
$positions = array();

while (($lastPos = strpos($html, $needle, $lastPos))!== false) {
    $positions[] = $lastPos;
    $lastPos = $lastPos + strlen($needle);
}

// Displays 3 and 10
foreach ($positions as $value) {
    echo $value ."<br />";
}
?>

Answer 2

Simple strpos_all() function.

function strpos_all($haystack, $needle_regex)
{
    preg_match_all('/' . $needle_regex . '/', $haystack, $matches, PREG_OFFSET_CAPTURE);
    return array_map(function ($v) {
        return $v[1];
    }, $matches[0]);
}

Usage: Simple string as needle.

$html = "ffffdasdfffffdasdffff";
$needle = "asdf";

$all_positions = strpos_all($html, $needle);
var_dump($all_positions);

Output:

array(2) {
  [0]=>
  int(3)
  [1]=>
  int(10)
}

Or with regex as needle.

$html = "ffffdasdfffffdasdffff";
$needle = "[d]{3}";

$all_positions = strpos_all($html, $needle);
var_dump($all_positions);

Output:

array(2) {
  [0]=>
  int(0)
  [1]=>
  int(7)
}

Answer 3

Without using regex, something like this should work for returning the string positions:

$html = "ffffdasdfffffdasdffff";
$needle = "asdf";
$lastPos = 0;
$positions = array();

while (($lastPos = strpos($html, $needle, $lastPos))!== false) {
    $positions[] = $lastPos;
    $lastPos = $lastPos + strlen($needle);
}

// Displays 3 and 10
foreach ($positions as $value) {
    echo $value ."<br />";
}