PHP invalid characters

miseria · 09-16-2005, 12:12 PM

Just a quicko, how can I define invalid characters for a user's input so that when a user registers to my site, they don't select a username such as:

"#~@L@N J0N3S~#"

lol, excuse the example. I only really want letters, numbers and hyphens to be used. Thanks

axilant · 09-16-2005, 12:17 PM

http://us2.php.net/ctype_alpha

I use these functions, but i have a class that i use them, but return false if its empty. I will think about posting it or not

Here it is... heh

PHP Code:

  function is_alpha($str = '') //alpha

    {

        if($str == "")

        {

            return false; //string empty

        }

        elseif(ctype_alpha($str) == true)

        {

            return true;

        }

        else

        {

            return false; //error, there must be a character than is not a letter!

        }

    }

    function is_num($str = '') //digits

    {

        if($str == "")

        {

            return false; //string empty!

        }

        elseif(ctype_digit($str) == true)

        {

            return true; //its a non-decimal number! (base 10)

        }

        else

        {

            return false; //error, there must be a character than is not a digit!

        }

    }

    function is_alnum($str = '') //alphanumeric

    {

        if($str == "")

        {

            return false; //string empty

        }

        elseif(ctype_alnum($str) == true)

        {

            return true; //this is 0-9, a-z!

        }

        else

        {

            return false; //error, there must be a character that is not a digit or letter!

        }

    }

Well some of it... i commented it pretty well, if you have any problems just ask.

miseria · 09-16-2005, 12:41 PM

Thanks very much for the help

moondog · 09-16-2005, 03:36 PM

You should also be able to do a POSIX match.

Something like this should work too:

PHP Code:

  $string = $_POST[string_to_test];

if(ereg('[^@.[:alnum:]]',$string)) {

  # code that catches invalid charactes here

}

In this example, the character class is negated with the beginning '^', and you would put any *VALID* characters in the class. In this case, you would allow the "@", a ".", and any alphanumbers (A-Z, a-z, 0-9)

-Bob

miseria · 09-17-2005, 04:10 AM

Thanks Bob, I am currently using

PHP Code:

  if (!ctype_alnum($username)) {

       

      echo '<script>alert("The username must consist of only alphanumeric characters (a-z 0-9).");</script>';

echo '<script>history.back(1);</script>';

exit;

   }

Is this wise?

sdsinc · 09-17-2005, 08:57 AM

I do like Bob suggested. A regular expression is fine and more flexible IMO.

For example I use code like this to test a user name, that means only letters and figures are allowed and the string must be between 4 and 16 chars long. It does the job nicely

PHP Code:

  if (!eregi("^([a-zA-Z0-9]{4,16})$", $username )) {

echo "Error: the user name is not valid blah...";

miseria · 09-17-2005, 11:00 AM

sdsinc, I just changed my code to the code you posted. But how do I make it case sensitive?

sdsinc · 09-17-2005, 11:02 AM

Well you just change eregi to ereg

miseria · 09-17-2005, 11:07 AM

Ah, simple as that eh? Thanks a lot

stscac · 09-17-2005, 07:46 PM

I use eregi a lot when validating email addresses and other forms of data - very useful.

If you want to see other ways it can be used, check out the PHP Manual documentation
http://us2.php.net/eregi

-Steve

09-16-2005, 12:12 PM	#1 (permalink)
miseria SQLdumpster.com Join Date: Jun 2005 Location: West Sussex, UK Posts: 545 205.50 NP$ (Donate)	PHP invalid characters Just a quicko, how can I define invalid characters for a user's input so that when a user registers to my site, they don't select a username such as: "#~@L@N J0N3S~#" lol, excuse the example. I only really want letters, numbers and hyphens to be used. Thanks __________________ !!!!!!! see something you like? Accepting offers for great affiliate websites !!!!!!! Free Databases for your Website \| All Things Playstation 3 Website Design Books \| Music While You Work? \| Computer Gadgets

09-16-2005, 12:17 PM	#2 (permalink)
axilant Account Closed Join Date: May 2004 Location: /etc/passwd Posts: 2,194 0.00 NP$ (Donate)	http://us2.php.net/ctype_alpha I use these functions, but i have a class that i use them, but return false if its empty. I will think about posting it or not Here it is... heh PHP Code: function is_alpha($str = '') //alpha { if($str == "") { return false; //string empty } elseif(ctype_alpha($str) == true) { return true; } else { return false; //error, there must be a character than is not a letter! } } function is_num($str = '') //digits { if($str == "") { return false; //string empty! } elseif(ctype_digit($str) == true) { return true; //its a non-decimal number! (base 10) } else { return false; //error, there must be a character than is not a digit! } } function is_alnum($str = '') //alphanumeric { if($str == "") { return false; //string empty } elseif(ctype_alnum($str) == true) { return true; //this is 0-9, a-z! } else { return false; //error, there must be a character that is not a digit or letter! } } Well some of it... i commented it pretty well, if you have any problems just ask. Last edited by axilant; 09-16-2005 at 12:28 PM.

09-16-2005, 12:41 PM	#3 (permalink)
miseria SQLdumpster.com Join Date: Jun 2005 Location: West Sussex, UK Posts: 545 205.50 NP$ (Donate)	Thanks very much for the help __________________ !!!!!!! see something you like? Accepting offers for great affiliate websites !!!!!!! Free Databases for your Website \| All Things Playstation 3 Website Design Books \| Music While You Work? \| Computer Gadgets

09-16-2005, 03:36 PM	#4 (permalink)
moondog NamePros Regular Join Date: Jun 2004 Posts: 476 3,677.00 NP$ (Donate)	You should also be able to do a POSIX match. Something like this should work too: PHP Code: `$string = $_POST[string_to_test]; if(ereg('[^@.[:alnum:]]',$string)) { # code that catches invalid charactes here }` In this example, the character class is negated with the beginning '^', and you would put any VALID characters in the class. In this case, you would allow the "@", a ".", and any alphanumbers (A-Z, a-z, 0-9) -Bob __________________ The mass purge has begun.

09-17-2005, 04:10 AM	#5 (permalink)
miseria SQLdumpster.com Join Date: Jun 2005 Location: West Sussex, UK Posts: 545 205.50 NP$ (Donate)	Thanks Bob, I am currently using PHP Code: `if (!ctype_alnum($username)) { echo '<script>alert("The username must consist of only alphanumeric characters (a-z 0-9).");</script>'; echo '<script>history.back(1);</script>'; exit; }` Is this wise? __________________ !!!!!!! see something you like? Accepting offers for great affiliate websites !!!!!!! Free Databases for your Website \| All Things Playstation 3 Website Design Books \| Music While You Work? \| Computer Gadgets

09-17-2005, 08:57 AM	#6 (permalink)
sdsinc Domains my Dominion Join Date: Aug 2005 Location: Web 1.0 Posts: 6,284 1,095.94 NP$ (Donate)	I do like Bob suggested. A regular expression is fine and more flexible IMO. For example I use code like this to test a user name, that means only letters and figures are allowed and the string must be between 4 and 16 chars long. It does the job nicely PHP Code: `if (!eregi("^([a-zA-Z0-9]{4,16})$", $username )) { echo "Error: the user name is not valid blah...";`

09-17-2005, 11:00 AM	#7 (permalink)
miseria SQLdumpster.com Join Date: Jun 2005 Location: West Sussex, UK Posts: 545 205.50 NP$ (Donate)	sdsinc, I just changed my code to the code you posted. But how do I make it case sensitive? __________________ !!!!!!! see something you like? Accepting offers for great affiliate websites !!!!!!! Free Databases for your Website \| All Things Playstation 3 Website Design Books \| Music While You Work? \| Computer Gadgets

09-17-2005, 11:02 AM	#8 (permalink)
sdsinc Domains my Dominion Join Date: Aug 2005 Location: Web 1.0 Posts: 6,284 1,095.94 NP$ (Donate)	Well you just change eregi to ereg

09-17-2005, 11:07 AM	#9 (permalink)
miseria SQLdumpster.com Join Date: Jun 2005 Location: West Sussex, UK Posts: 545 205.50 NP$ (Donate)	Ah, simple as that eh? Thanks a lot __________________ !!!!!!! see something you like? Accepting offers for great affiliate websites !!!!!!! Free Databases for your Website \| All Things Playstation 3 Website Design Books \| Music While You Work? \| Computer Gadgets

09-17-2005, 07:46 PM	#10 (permalink)
stscac A Wealth of Knowledge Join Date: Aug 2004 Posts: 3,794 47.60 NP$ (Donate)	I use eregi a lot when validating email addresses and other forms of data - very useful. If you want to see other ways it can be used, check out the PHP Manual documentation http://us2.php.net/eregi -Steve

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