如何使用preg_replace regex将*转换为HTML

Question

I have paragraphs of texts with this kind of markup in them:

text1 *text2* text3

I need to turn them into

text1 <strong>text2</strong> text3

I tried this code

$pattern = '~\*(.*)\*~'; 
$replacement = '<strong>\1</strong>'; 
$str = preg_replace($pattern, $replacement, $str);

It doesn't recognize the second, closing asterisk. The closing strong" html tag only appears at the next (third) asterisk much later in the same text.

What am I missing?

Update: Avinash's pattern worked for the issue, but here is a related one

I used the same pattern (the first of the two) to replace underscores with tags. But the same paragraphs included images with syntax like <img src="/my_image.jpg" width="700" height="300"> How do I avoid this regex turning those underscores? (The width/height numbers vary, not constant.)

E.g. from a text like this

Lorem ipsum dolor sit amet, <img src="/my_image.jpg" width="700" height="300">  adipiscing elit. _Fusce pharetra_ a dui nec interdum. 

I would like to get this

Lorem ipsum dolor sit amet, <img src="/my_image.jpg" width="700" height="300">  adipiscing elit. <em>Fusce pharetra</em> a dui nec interdum.

Answer 1

You need to add the quantifier ? after * which was present inside the capturing group to do a shortest possible match,

$pattern = '~\*(.*?)\*~'; 

OR

$pattern = '~\*[^*]*\*~';