How to Extract Substrings in PHP Using Different Delimiter Types?

Determining Substrings in PHP

In PHP, obtaining substrings within specified delimiters can be achieved using various methods. For instance, if the demarcation delimiters are identical at both ends (e.g., [foo] and [/foo]), the following approach will suffice:

function get_string_between($string, $start, $end) {
    $string = ' ' . $string;
    $ini = strpos($string, $start);
    if ($ini == 0) {
        return '';
    }
    $ini += strlen($start);
    $len = strpos($string, $end, $ini) - $ini;
    return substr($string, $ini, $len);
}

To illustrate, consider the following example:

$fullstring = 'this is my [tag]dog[/tag]';
$parsed = get_string_between($fullstring, '[tag]', '[/tag]');
echo $parsed; // (result = dog)

Additionally, if the delimiters are unique (e.g., [foo] and [/foo2]), a modified function can be employed:

function get_inner_substring($str, $delim) {
    $results = array();
    $delim_len = strlen($delim);
    $pos = strpos($str, $delim);
    while ($pos !== false) {
        $pos_end = strpos($str, $delim, $pos + $delim_len);
        if ($pos_end !== false) {
            $results[] = substr($str, $pos + $delim_len, $pos_end - $pos - $delim_len);
            $pos = strpos($str, $delim, $pos_end + $delim_len);
        } else {
            break;
        }
    }
    return $results;
}

Using this function, multiple substrings can be extracted from a string separated by different delimiters:

$string = " foo I like php foo, but foo I also like asp foo, foo I feel hero  foo";
$arr = get_inner_substring($string, "foo");
print_r($arr); // (result = ['I like php', 'I also like asp', 'I feel hero'])

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