Question

I was wondering if the codes below are the correct way to check for a street address, email address, password, city and url using preg_match using regular expressions?

And if not how should I fix the preg_match code?

 preg_match ('/^[A-Z0-9 \'.-]{1,255}$/i', $trimmed['address']) //street address
 preg_match ('/^[\w.-]+@[\w.-]+\.[A-Za-z]{2,6}$/', $trimmed['email'] //email address
 preg_match ('/^\w{4,20}$/', $trimmed['password']) //password
 preg_match ('/^[A-Z \'.-]{1,255}$/i', $trimmed['city']) //city
 preg_match("/^[a-zA-Z]+[:\/\/]+[A-Za-z0-9\-_]+\\.+[A-Za-z0-9\.\/%&=\?\-_]+$/i", $trimmed['url']) //url

Answer 1

Your street address: ^[A-Z0-9 \'.-]{1,255}$

• you need not escape the single quote.
• since you have a dot in the char
  class, it will allow all char (except
  newline). So effective your regex becomes ^.{1,255}$
• you are allowing it to be of min
  length of 1 and max of length 255. I
  would suggest you to increase the min
  length to something more than 1.

Your email regex: ^[\w.-]+@[\w.-]+\.[A-Za-z]{2,6}$

• again you are having . in the char
  class. fix that.

Your password regex: ^\w{4,20}$

• allows for a passwd of length 4 to 20
  and can contain only alphabets(upper
  and lower), digits and underscore. I would suggest you to allow
  special char too..to make your
  password stronger.

Your city regex: ^[A-Z \'.-]{1,255}$

• has . in char class
• allows min length of 1 (if you want
  to allow cities of 1 char length this
  is fine).

EDIT:

Since you are very new to regex, spend some time on Regular-Expressions.info