Regular expression to detect Internet Explorer 11

Question

I am using this preg_match string

preg_match(\'/Trident/7.0; rv:11.0/\',$_SERVER[\"HTTP_USER_AGENT\"]

to detect IE11 so I can

Answer 1

The / after Trident is being treated as a delimiter. You could escape it:

preg_match('/Trident\/7.0; rv:11.0/',$_SERVER["HTTP_USER_AGENT"]

Better, however, would be not to use preg_match: you don't need it. All you're doing is looking for an invariant substring, which can be done with strpos:

if (false !== strpos($_SERVER["HTTP_USER_AGENT"], '/Trident/7.0; rv:11.0/')) {