Simple regex help?

[extrovertive]

I want a regex such that it will not accept a number of special characters in front..and letters only in front..with numbers ok. Underscore is fine.

 

Sort of like a username type of field.

 

Anyone help?

[rhodesa]

you may want to try rewording that...it's very confusing how you put it. but if i have disciphered the message correctly....

 

-First character must be a letter

-Numers/Letters/Underscores in the rest are fine

 

^[a-zA-Z]\w*$

[The Little Guy]

I thing he also wants to allow numbers and underscores:

 

/^(_|[a-zA-Z0-9])\w*$/

[nrg_alpha]

I thing he also wants to allow numbers and underscores:

 

/^(_|[a-zA-Z0-9])\w*$/

 

There is no need for alternations in this case.. you can simply use \w throughout (assuming it can start with an underscore or any number or letter:

 

#^\w+$#

 

Granted, depending on the locale, \w actually can match more than simply a-zA-Z0-9_.. it can also potentially match characters like à ò ì ù è by example (there are even more). So if it can start with an underscore, letter or number and must be any and only any of those throughout the string, then a simple character class with those would suffice:

 

#^[a-z0-9_]+$#i