Sometimes we don’t care exactly WHAT characters are in a text, just that there are SOME characters. Enter the wildcard
.! Wildcards will match any single character (letter, number, symbol or whitespace) in a piece of text. They are useful when we do not care about the specific value of a character, but only that a character exists!
Let’s say we want to match any 9-character piece of text. The regex
......... will completely match
marsupial! Similarly, the regex
I ate . bananas will completely match both
I ate 3 bananas and
I ate 8 bananas!
What happens if we want to match an actual period,
.? We can use the escape character,
\, to escape the wildcard functionality of the
. and match an actual period. The regex
Howler monkeys are really lazy\. will completely match the text
Howler monkeys are really lazy..
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!