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 like the character position so I can loop through the list to return some data after the string.

The strpos function only returns the first occurrence. How about returning all of them?

Answer 1

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

$html = "dddasdfdddasdffff";
$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 />";
}

Answer 2

You can call the strpos function repeatedly until a match is not found. You must specify the offset parameter.

Note: in the following example, the search continues from the next character instead of from the end of previous match. According to this function, aaaa contains three occurrences of the substring aa , not two.

function strpos_all($haystack, $needle) {
    $offset = 0;
    $allpos = array();
    while (($pos = strpos($haystack, $needle, $offset)) !== FALSE) {
        $offset   = $pos + 1;
        $allpos[] = $pos;
    }
    return $allpos;
}
print_r(strpos_all("aaa bbb aaa bbb aaa bbb", "aa"));

Output:

Array
(
    [0] => 0
    [1] => 1
    [2] => 8
    [3] => 9
    [4] => 16
    [5] => 17
)

Answer 3

Its better to use substr_count . Check out on php.net

Answer 4

function getocurence($chaine,$rechercher)
        {
            $lastPos = 0;
            $positions = array();
            while (($lastPos = strpos($chaine, $rechercher, $lastPos))!== false)
            {
                $positions[] = $lastPos;
                $lastPos = $lastPos + strlen($rechercher);
            }
            return $positions;
        }

Answer 5

Use preg_match_all to find all occurrences.

preg_match_all('/(\$[a-z]+)/i', $str, $matches);

For further reference check this link .

Answer 6

This can be done using strpos() function. The following code is implemented using for loop. This code is quite simple and pretty straight forward.

<?php

$str_test = "Hello World! welcome to php";

$count = 0;
$find = "o";
$positions = array();
for($i = 0; $i<strlen($str_test); $i++)
{
     $pos = strpos($str_test, $find, $count);
     if($pos == $count){
           $positions[] = $pos;
     }
     $count++;
}
foreach ($positions as $value) {
    echo '<br/>' .  $value . "<br />";
}

?>

Answer 7

Salman A has a good answer, but remember to make your code multibyte-safe. To get correct positions with UTF-8, use mb_strpos instead of strpos:

function strpos_all($haystack, $needle) {
    $offset = 0;
    $allpos = array();
    while (($pos = mb_strpos($haystack, $needle, $offset)) !== FALSE) {
        $offset   = $pos + 1;
        $allpos[] = $pos;
    }
    return $allpos;
}
print_r(strpos_all("aaa bbb aaa bbb aaa bbb", "aa"));

Answer 8

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 = "dddasdfdddasdffff";
$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 = "dddasdfdddasdffff";
$needle = "[d]{3}";

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

Output:

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

Answer 9

<?php
$mainString = "dddjmnpfdddjmnpffff";
$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 10

Another solution is to use explode() :

public static function allSubStrPos($str, $del)
{
    $searchArray = explode($del, $str);
    unset($searchArray[count($searchArray) - 1]);
    $positionsArray = [];
    $index = 0;
    foreach ($searchArray as $i => $s) {
        array_push($positionsArray, strlen($s) + $index);
        $index += strlen($s) + strlen($del);
    }
    return $positionsArray;
}