Ansvered /如何在PHP函数中使用数据库中的内容？

I have a PHP function which converts #Hashtag into a link...

function convertHashtags($str) {
 $regex = "/#+([a-zA-Z0-9_]+)/";
 $str = preg_replace($regex, '<a href="hashtag.php?tag=$1">$0</a>', $str);
 return($str);
}

It work properly when I use it with a common string

$string = "Hello #World";
$string = convertHashtags($string);

(in this case an output would be: Hello #World

But when I'm trying to insert something from my database to that string it displays, but without that function's effect…

$string = $row["content"];
$string = convertHashtags($string);

(an output: Hello #World)

I am new to the PHP and MySQL stuff… Certainly, there are many things I don't know yet :D

What's wrong with this function?

Thanks!

$string = $row["content"];
$string = (string)$string;
$string = convertHashtags($string);

Use the above code and it will work.

Oh well, I just add new element to a database and it works!

I was testing it on old elements, they was inserted before I wrote the function.

I should try it before writing a this, my bad… thanks for help anyway!

function convertHashtags($str){
      list($str1, $str2) = explode("#", $str) ;
      $str2 = '<a href="http://www.hashtag.php?tag='.$str2.'">#'.$str2.'</a>';
      $str = $str1." ".$str2 ;
      return($str);
}

Can you use the above function and test with database entry?