validating user input

[DCM]

Hi, what is they best way to validate user input of strings?

 

A couple of examples would be :

 

1> If i wanted to check for the existance on the coma ',' character in a string and replace it with a dash '-' character?

 

2> To check wether a user has entered a valid ip address in the form of x.x.x.x where x can range from 0-255?

 

I think i may need ereg/preg to do this but i have no idea about how to layout the syntax.

 

Thanks for looking.

[Pawn]

1)

$str = str_replace(",","-",$str)

2) I'm no regex guru, but a quick Google turns up plenty of options.

[Andy-H]

$str = str_replace(',', '-', $str); //replace commas with hyphens

if (preg_match( "/^(([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]).){3}([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/", $ip))
{
   echo 'Valid IP address';
}
else
{
   echo 'Invalid IP address.';
}

[DCM]

Thanks that works although i am having a real problem interpreting the syntax of that regular expression, need to do some backgroung reading i think on PH and regex.

[DarkMantis]

Thanks that works although i am having a real problem interpreting the syntax of that regular expression, need to do some backgroung reading i think on PH and regex.

 

 

 

Here is an amazing little cheat sheet to learn from. That's how I learnt. Amongst a few other sites

 

http://www.addedbytes.com/cheat-sheets/regular-expressions-cheat-sheet/

[DCM]

Thats great thanks a lot.