Convert [audio ] to tag in core php

I am in trouble while converting a link to tag . here is

I am trying

https://abcd.com/wp-content/uploads/sites/2/2020/03/classical-demo.mp3

to convert

<a href="https://abcd.com/wp-content/uploads/sites/2/2020/03/classical-demo.mp3"></a>

I am use str_replace, following are the code one by one.

$a = '';

echo str_replace("[","<",$a);
echo str_replace("]",">",$a);
echo str_replace("audio","a",$a);
echo str_replace("mp3","href",$a);
exit();

But still getting no result.

Is any another way for solving this? any one having solution for this please help me to solve out this problem.

Answer

I’m not PHP developer, but I think you can use following code:

$a = '';

$b = str_replace("[","<", $a);
$b = str_replace("]",">", $b);
$b = str_replace("audio","a", $b);
// you need to replace mp3=, not mp3, as you have 2 of it
$b = str_replace("mp3=","href=", $b);

// optional
$b = str_replace("><",">link text<", $b);

echo $b;
exit();

$b will be: <a href="https://abcd.com/wp-content/uploads/sites/2/2020/03/classical-demo.mp3">link text</a>

See it in action thanks to @Phil