Question

I need to build a regex that allows only letters and hyphens, but it needs to require the hyphens.

I tried:

• ^[a-z]+[a-z\-]+[a-z]+$ (the match without hyphens pass)
• ([A-Za-z\-]+) (the match without hyphens pass too)
• [a-zA-Z][\-]+ (it didn’t work)

Could someone write it to me?

Thanks in advance.

Answer 1

You need a look ahead:

^(?=.*-)[a-zA-Z-]+$

That little expression (?=.*-) is a “look ahead”, which is a non-consuming assertion that .*- appears somewhere ahead, which means “there needs to be hyphen in the input”

Also, when put first or last the hyphen is a literal hyphen that doesn’t need escaping, otherwise a hyphen denotes a range.