Updated: 19 May 2025
Quantifiers
https://learn.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions
| Greedy quantifier | Lazy quantifier | |
|---|---|---|
* |
*? |
Matches zero or more times. |
+ |
+? |
Matches one or more times. |
? |
?? |
Matches zero or one time. |
{n} |
{n}? |
Matches exactly n times. |
{n,} |
{n,}? |
Matches at least n times. |
{,m} |
{,m}? |
Matches up to m times. |
{n,m} |
{n,m}? |
Matches from n to m times. |
Candidate regex for an email address. Credit to this Stackoverflow article
(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9]))\.){3}(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])