quantifiers

Quantifiers

Quantifier	Meaning
*	Match 0 or more times
+	Match 1 or more times
?	Match 1 or 0 times
{n}	Match exactly n times
{n,}	Match at least n times
{n,m}	Match at least n but not more than m times

Greed

The * and + are considered greedy because they match all they can before allowing the next part of the pattern to attempt matching. You can add a ? to turn off this behavior and match as little as possible. Ex: /\w+?/ or /\w*?/

Exercises

Regex101 | Debuggex

• Match a floating point number (with some extra restrictions)
• Can start with a -
• Has 0 or more digits (0|1|2|3|4|5|6|7|8|9 can be replace with \d)
• An optional . (Make sure you escape \. it, or it will match one of your digits by mistake)
• More digits. You probably want to force at least one here in case no period ever shows.
• Match whole numbers >= 1000
• Match whole numbers where 1000 <= n < 10,000
• Match whole numbers where 1000 <= n < 1,000,000
• Find the number substrings that start and end with 8. Ex: 885832834848 would find 88, 8328, 848, but not the whole string

Exercise Text

12
843720
3813
1.234
-4.5
-4
-.5
-0
38.
82983271993
NaN
-4.4827e-2
8437284773984342448937247292837493729347882738
885832834848