Test if string is URL encoded in PHP

Question

How can I test if a string is URL encoded?

Which of the following approaches is better?

• Search the string for characters which would be encoded, which

Answer 1

I am using the following test to see if strings have been urlencoded:

if(urlencode($str) != str_replace(['%','+'], ['%25','%2B'], $str))

If a string has already been urlencoded, the only characters that will changed by double encoding are % (which starts all encoded character strings) and + (which replaces spaces.) Change them back and you should have the original string.

Let me know if this works for you.