if http:// is in string then leave it, else if not add it

Question

I have a input that you enter a URL, i basically want to write some php that says if the domain containts \"http://\" then leave it be, else if not then add it to the beginn

Answer 1

"http://" then leave it be, else if not then add it to the beginning.

How about adding adding it regardless? I find that to be easier: