I am trying to allow only A-Z, a-z, 0-9, -, _
I'm using the following expression which is working:
preg_match('/^[a-zA-Z0-9-_]+$/i', $_POST['sign_up_username'])
Is this the correct way to go about doing this?
Asked
Active
Viewed 3,150 times
0
-
Your question is too broad. Please point out any problems or challenges you are facing with this. – AKS May 23 '16 at 06:13
-
@AKS Basically will my regex only allow A-Z both upper and lowercase, numbers, dashes, and underscores. I just started working with regex a few days ago so I'm still very uncertain of how to do stuff with them. – Coilerz May 23 '16 at 06:16
-
Why would one want to limit user account names in that a narrow manner? – arkascha May 23 '16 at 06:16
-
Not account names, usernames. I don't want my users to have names like "@Bob&Joe*youtube" – Coilerz May 23 '16 at 06:19
2 Answers
5
The regex is incorrect. Move - in last or beginning or escape it in character class because - have special meaning inside character class. It denotes range within character class. You can use
^[-a-zA-Z0-9_]+$
Also
\w = [a-zA-Z0-9_]
So, you can use
^[\w-]+$
Also, there is no need of i modifier and finally yes it will allow only A-Z both upper and lowercase, numbers, dashes, and underscores
This will suffice in PHP
preg_match('/^[\w-]+$/', $_POST['sign_up_username'])
rock321987
- 10,942
- 1
- 30
- 43
-
Could you give me an example in terms of `preg_match`? I'm still very uncertain about the slashes at the end and beginning. – Coilerz May 23 '16 at 06:18
-
@Coilerz updated..you can use if condition with `preg_match`.`/` is just for denoting what exists between `/../` to be treated as regex – rock321987 May 23 '16 at 06:21
-1
if(preg_match('/^[a-zA-Z0-9-_]+$/i', $str) == 1)
{
// string only contain the a to z , A to Z, 0 to 9, -_
echo "yes";
}
else
{
echo " no";
}
Yogesh Singasane
- 283
- 3
- 12