How to get and change URL variable PHP

Question

Hi could anyone help me with this I have a URL like

parent/child/a=1&b=2$c=3

then I have a link that would add variable to that URL

Answer 1

Here you have not take care of the double quotation. Replace that with the following code and then check.

LINK 1

And also check in firebug that what URL is in href each time.