regex - How to escape $ in PHP using preg_replace?

Question

I am using preg_replace to escape special characters:

$tmpStr=preg_replace("/?/", "?", $tmpStr);
$tmpStr=preg_replace("/#/", "#", $tmpStr);
$tmpStr=preg_replace("/^/", "^", $tmpStr);
$tmpStr=preg_replace("/&/", "&", $tmpStr);
$tmpStr=preg_replace("/*/", "*", $tmpStr);
$tmpStr=preg_replace("/(/", "(", $tmpStr);
$tmpStr=preg_replace("/)/", ")", $tmpStr);
$tmpStr=preg_replace("///", "/", $tmpStr); 

But I am not able to escape $ using the same function:

$tmpStr=preg_replace("/$/", "$", $tmpStr);

And also when I use the above statement all the spaces get replaced by $ and $ is not getting escaped.

How do I escape the dollar sign correctly?

Answer 1

I would strongly recommend using preg_quote() instead.