How do I match a text which can contain - or an underscore using regular expression?

Question

I want the username to be any characters with _ or - in it but this in Perl is not working, why is it?

if ("kunjaaN-" =~ /^[a-zA-Z-_]{1,7}$/)
{ print "equal" ; }

Answer 1

It's not working because kunjaaN- is eight characters, and you're limiting yourself to 1..7

For a username, why not increase the limit to something decent?

Also, if you want _ included you need to include that in your character class.

Try this regex:

^[a-zA-Z_-]{1,16}\z

Note:
Inside character classes, the - character can have special meaning. For example, [a-z] means 'the range of characters starting with a and ending in z', whilst [az-] means 'either a or z or -'.

To make a - non-special you can place it at the start or end of a class, or escape it with a backslash. [a\-z] will match a or z or -.
Escaping is generally preferred since it avoids accidents if extra characters are inadvertently added to the end of the class.

Answer 2

If you don't want to allow a possible newline at the end of your string, use the \z end of string anchor instead of the $ anchor:

 /^[a-z_-]{1,8}\z/i