If you're trying to build the a `base_url()` function, [this answer](http://stackoverflow.com/a/17201261/1438393) should get you started. The code in your question isn't working because you can't call functions inside single-quotes. Use concatenation as shown in @hsz's answer.
– Amal MuraliApr 18 '14 at 10:18
@ShankarDamodaran: I'm aware of the function, but I wasn't sure if the OP was using CI (as the question wasn't tagged so).
– Amal MuraliApr 18 '14 at 10:20
@Christian How do you know that the OP uses CI framework? Please don't add tags unless it's obvious that the question is related to that specific tag.
– Amal MuraliApr 18 '14 at 10:27