How can PHP developers effectively convert allowed HTML tags in user input to BBCode for storage and then back to HTML for display?

To convert allowed HTML tags in user input to BBCode for storage and then back to HTML for display, PHP developers can use functions like strip_tags() to remove disallowed HTML tags, and then use str_replace() or regular expressions to convert the remaining HTML tags to BBCode. When displaying the content, the BBCode can be converted back to HTML using str_replace() or regular expressions. 

```php
// Function to convert allowed HTML tags to BBCode for storage
function convertToBBCode($input) {
    $allowed_tags = '<b><i><u><a>';
    $input = strip_tags($input, $allowed_tags);
    $input = str_replace('<b>', '[b]', $input);
    $input = str_replace('</b>', '[/b]', $input);
    $input = str_replace('<i>', '[i]', $input);
    $input = str_replace('</i>', '[/i]', $input);
    $input = str_replace('<u>', '[u]', $input);
    $input = str_replace('</u>', '[/u]', $input);
    $input = preg_replace('/<a href="(.*?)">(.*?)<\/a>/', '[url=$1]$2[/url]', $input);
    
    return $input;
}

// Function to convert BBCode back to HTML for display
function convertToHTML($input) {
    $input = str_replace('[b]', '<b>', $input);
    $input = str_replace('[/b]', '</b>', $input);
    $input = str_replace('[i]', '<i>', $input);
    $input = str_replace('[/i]', '</i>', $input);
    $input = str_replace('[u]', '<u>', $input);
    $input = str_replace('[/u]', '</u>', $input);
    $input = preg_replace('/\[url=(.*?)\](.*?)\[\/url\]/', '<a href="$1">$2</a>', $input);
    
    return $input;
}

// Example of converting user input to BBCode for storage
$user_input = '<b>Hello</b> <a href="https://example.com">Click here</a>';
$bbcode = convertToBBCode($user_input);
echo $bbcode; // Output: [b]Hello[/b] [url=https://example.com]Click here[/url]

// Example of converting BBCode back to HTML for display
$html_output

Keywords

PHP HTML tags BBCode storage display

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