PHP regular delete html specified tag and the content inside the tag

test example

$str='<div><p>here is the p tag</p><img src="" alt="here is the img tag"><a href="">here is the a tag</a><br ></div>';

1. Delete all or keep the specified html tags

The function strip_tags that comes with php can meet the requirements

echo strip_tags($str,'<p><a>');
//Output: <p>here is the p tag</p><a href="">here is the a tag</a>

2. Delete the specified html tag

How to use: strip_html_tags($tags,$str)

<?php

function strip_html_tags($tags, $str)
{
    $html = array();
    foreach ($tags as $tag) {
        $html[] = "/(<(?:\/" . $tag . "|" . $tag . ")[^>]*>)/i";
    }
    $data = preg_replace($html, '', $str);
}

echo strip_html_tags(array('p','img'),$str);
//Output: <div>here is the p tag <a href="">here is the a tag</a><br></div>;

3. Remove tags and tag content

How to use: strip_html_tags($tags,$str)

<?php
function strip_html_tags($tags,$str){
    $html=array();
    foreach ($tags as $tag) {
        $html[]='/(<'.$tag.'.*?>[\s|\S]*?<\/'.$tag.'>)/';
    }
    $data=preg_replace($html,'',$str);
}
echo strip_html_tags(array('a','img'),$str);
//output <div><p>here is the p tag</p><img src="" alt="here is the img tag"><br></div>;

4. Delete the specified tag; delete or retain the content in the tag

How to use: strip_html_tags($tags,$str,$content)

<?php
/**
 * Delete the specified tags and content
 * @param array $tags array of tags to delete
 * @param string $str data source
 * @param string $content Whether to delete the content in the tag, the default is 0 to keep the content, 1 to not keep the content
 * @return string
 */
function strip_html_tags($tags,$str,$content=0){
    if($content){
        $html=array();
        foreach ($tags as $tag) {
            $html[]='/(<'.$tag.'.*?>[\s|\S]*?<\/'.$tag.'>)/';
        }
        $data=preg_replace($html,'',$str);
    }else{
        $html=array();
        foreach ($tags as $tag) {
            $html[]="/(<(?:\/".$tag."|".$tag.")[^>]*>)/i";
        }
        $data=preg_replace($html, '', $str);
    }
    return $data;
}
echo strip_html_tags(array('a'),$str,1);
//output <div><p>here is the p tag</p><img src="" alt="here is the img tag"><br></div>;
?>