Question

Say you have a pattern like this:

@[a-z]+\s[\d] 

is it useful to have something like this:

(@[a-z]+\s[\d])

in any situation? Is there any difference between them? How so?

Answer 1

The () are used for capturing data. If you try to match "My name is John" without capturing:

/My name is [A-Z][a-z]+/

Then the result would simply be the string:

("My name is John")

If you want to capture the name separately from the result then you can use the () like this:

/My name is ([A-Z][a-z]+)/

This will return the entire match (it is a convention to always return the entire match as the first result item), and it will also return the captured name, like so:

("My name is John", "John")

If we want to capture the first and last name in "My name is John Doe" then we can do it like this:

/My name is ([A-Z][a-z]+) ([A-Z][a-z]+)/

The result:

("My name is John Doe", "John", "Doe")

So, to answer your question, there is really no difference between the two expressions. The first will just match a string, while the second will match and capture it (in this case you would basicaly just end up with two identical results).