In the strings and console section 9 (Dot Notation) it is said that len() is not exclusive to strings and can be used for other data types so I tried this:

```
pi = 3.14
print len(pi)
```

and it does not work. Clrearly it does not work for the integer data type.

Then again I tried

```
pi = 3.14
if = str(pi)
print len(if)
```

and still it won't work. So can anybody please tell me why is this so? And what is the difference between functions that use dot notation and brackets? Also, with so many functions out there how do I know if it requires the dot notation or the bracket use?

Thanks!