Regex match at least 3 letters

Question

I need a regex to match

• at least 3 letters
• min length: 3
• may also contain [0-9_-] if there are 3 letters in string already (true if str1, str_, str-,
  ---------str, -s-t-r- but false if 123, ---, ___, 123---, 123___, ---___)

I did this ^(?=.*[a-zA-Z_-].*)(?=.*\d.*)[\w]{3,}$ but it doesn't match strings like str1, 1str, str-, str_.

Answer 1

Try this: [0-9_-]*[a-zA-Z]{3,}[0-9_-]*. This assumes that your string must have at least 3 letters.

Answer 2

This matches what you need:

([0-9_-]*[a-z][0-9_-]*){3}

Matches:

str1
str_
1str
str-

Does not match:

123
---
___
123---
123___
---___

Do these terms come alone or are they separated by spaces, commas?

If they come one by one, you should use enclose that regex between ^ and $.