Learn
Do you feel those regular expression superpowers coursing through your body? Do you just want to scream ah+
really loud? Awesome! You are now ready to take these skills and use them out in the wild. Before beginning your adventures, let’s review what we’ve learned.
- Regular expressions are special sequences of characters that describe a pattern of text that is to be matched
- We can use literals to match the exact characters that we desire
- Alternation, using the pipe symbol
|
, allows us to match the text preceding or following the|
- Character sets, denoted by a pair of brackets
[]
, let us match one character from a series of characters - Wildcards, represented by the period or dot
.
, will match any single character (letter, number, symbol or whitespace) - Ranges allow us to specify a range of characters in which we can make a match
- Shorthand character classes like
\w
,\d
and\s
represent the ranges representing word characters, digit characters, and whitespace characters, respectively - Groupings, denoted with parentheses
()
, group parts of a regular expression together, and allows us to limit alternation to part of a regex - Fixed quantifiers, represented with curly braces
{}
, let us indicate the exact quantity or a range of quantity of a character we wish to match - Optional quantifiers, indicated by the question mark
?
, allow us to indicate a character in a regex is optional, or can appear either0
times or1
time - The Kleene star, denoted with the asterisk
*
, is a quantifier that matches the preceding character0
or more times - The Kleene plus, denoted by the plus
+
, matches the preceding character1
or more times - The anchor symbols hat
^
and dollar sign$
are used to match text at the start and end of a string, respectively
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 telephone numbers listed below “Match these strings”. This is a tricky one, so have some fun. Good luck!
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