Find anything between value="something" PHP

我需要在value="的引号之间找到字符/字母，然后更改它。

我知道这是可能的学习如何找到"未知数据"与正则表达式等

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);
}
$fullstring = "this is my [tag]dog[/tag]";
$parsed = get_string_between($fullstring, "[tag]", "[/tag]");
echo $parsed; // (result = dog)
$newstring = str_replace($parsed,"new phrase or whatever",$fullstring);
echo $newstring; // (result = this is my [tag]new phrase or whatever[/tag])