Remember when we were in love with baboons and gorillas a few exercises ago? We were able to match either baboons
or gorillas
using the regex baboons|gorillas
, taking advantage of the |
symbol.
But what if we want to match the whole piece of text I love baboons
and I love gorillas
with the same regex? Your first guess might be to use the regex I love baboons|gorillas
. This regex, while it would completely match the string I love baboons
, would not match I love gorillas
, and would instead match gorillas
. This is because the |
symbol matches the entire expression before or after itself.
Grouping to the rescue! Grouping, denoted with the open parenthesis (
and the closing parenthesis )
, lets us group parts of a regular expression together, and allows us to limit alternation to part of the regex.
The regex I love (baboons|gorillas)
will match the text I love
and then match either baboons
or gorillas
, as the grouping limits the reach of the |
to the text within the parentheses.
These groups are also called capture groups, as they have the power to select, or capture, a substring from our matched text.
Instructions
The interactive applet in the browser allows you to enter a regular expression and see if it matches a string of text. If a character is matched, you’ll see it highlighted in green. If there’s a checkmark next to the string, you’ve completely matched the whole piece of text!
Enter a regular expression that matches each of the strings listed below “Match these strings” and does NOT match any of the strings listed below “Don’t match these strings.”
When you’ve entered a regular expression that matches the appropriate strings, a key will appear in the browser. Add the key to the end of the URL in the code editor and run the code to unlock the next exercise!