how to test string whether it contains special characters

[exoskeleton]

please help dear experts on how to test string especially in username for example wheter it contains special charater and will return invalid!

please help...TIA

[devsusen]

I prefer preg_match() in such cases. Can u tell us what sort of special chars u like to search within names?

susen

[tolkienarda]

please help dear experts on how to test string especially in username for example wheter it contains special charater and will return invalid!

please help...TIA

one simple way to do that is with the strpos() function. here is a short tutorial of how it works

$username = 'frank!anderson';
$pos = strpos($username, "!");
if ($pos == -1)
{
   print 'dont put ! in your usernames you silly person';
}
else
{
   print 'everything is super cool and what not';
}

i hope that helps other functions to look at include
strcmp()
strstr()
documentation can be found at php.net/function name
ex
http://www.php.net/strcmp

eric

oh and devsusen is right pregmatch is probably the most standard way to this. but is far to complicated for a simple mind such as myself so i always use these dumbed down versions.

[exoskeleton]

I prefer preg_match() in such cases. Can u tell us what sort of special chars u like to search within names?

susen

thank you sir devsusen.. :) but how can i add characters to preg_match() in order to find not just 1 special characters like the split function that only enclosed by "[ ]" like

split('[/.-]', $date);

in order to find not just 1 character in an expression or given string?

i tried like for example:

$string = '#richa@rd';
preg_match('/!@#$%^&*()/','$string');

but cant able to find anything....and he can find something if like this:

$string = 'richard';
preg_match('/chard/','$string');

[exoskeleton]

one simple way to do that is with the strpos() function. here is a short tutorial of how it works

$username = 'frank!anderson';
$pos = strpos($username, "!");
if ($pos == -1)
{
   print 'dont put ! in your usernames you silly person';
}
else
{
   print 'everything is super cool and what not';
}

i hope that helps other functions to look at include
strcmp()
strstr()
documentation can be found at php.net/function name
ex
http://www.php.net/strcmp

eric

oh and devsusen is right pregmatch is probably the most standard way to this. but is far to complicated for a simple mind such as myself so i always use these dumbed down versions.

same with this sir... how can i add special characters to find not just 1.. yes this is possible if only 1 special character to find...

thank you sir

[tolkienarda]

well my advice would be to go back to devsusen's idea. and what preg_match as i am sure you know uses regular expressions and a good tutorial on the complex world of regex is
http://weblogtoolscollection.com/regex/regex.php
and there are many more but this is php based and a good starting place
unfortunatly the functions i listed earlier can only look for one expression at a time. if you had an array of strings you were looking for say

you can use a loop

$string = 'adsf@ASDF!fdsa#FDSA%';
$lookfor[0] = '!'
$lookfor[1] = '@'
$lookfor[2] = '#'
$lookfor[3] = '%'
$i = 0;
while ($i < 4)
{
   $var = strpos($string, $lookfor[$i]);
   if ($var != -1)
   {
      echo 'passed test for $lookfor[$i]';
   }else
   {
       echo 'silly person none of those silly charcters';
   }
 
}

now i typed this code into this forum directly so there might be a missing semi colon or paren but the basic logic will work.
(preg_match and regular expressions i have avoided for my entire programing carear because the confuse me to no end but if you can figure them out i urge you to go in that direction because they are extreamley powerful and i always feel stupid when i have a problem that could be easily solved with regex but i cannot do it without loops and if statements)

eric

[exoskeleton]

thank you sir... :)

[devsusen]

hi,

how can i add characters to preg_match() in order to find not just 1 special characters

To check multiple special characters u can use preg_match too. There u need to specify the characters u like to check using separator. I'm giving u an example.

preg_match('/[\s|\n|\t|*|@|&]/', $anyVariable); 

susen

[tolkienarda]

hmm i realy need to learn that preg_match stuff it is way simpler than my loops and such.

eric

[exoskeleton]

thank you sir susen and sir eric...it really helps.....more power guys

[NIKHILUNNIKRISHNAN]

I Didnt Get It Done Using "strpos". In Which Namespace Is That Function Defined ?

[NIKHILUNNIKRISHNAN]

Can I Have Any Alternate Methods For The Same ?

[RodanMedia]

This was valuable to me, as we're designing a new social network site. But here's my modification of that script, checking for a specified set of values in an array, then checking for an empty position.

This is the code exactly as it is in action. To see it working, go to <link removed>. I dare you to get by it.

$forbid = array(' ','--', '-', '&quot;','!','@','#','$','%','^','&','*','(',')','_','+','{','}','|',':','"','<','>','?','[',']','\\',';',"'",',','.','/','*','+','~','`','=');
    $i = 0;
    while ($i < 37) {
        $var = strpos($userID, $forbid[$i]);
        if (!empty($var)) {
            $var++;
            echo "Position " . $var . " forbidden character.<br><font color='#FF0000'>Character detected is <strong>'" . $forbid[$i] . "'</strong></font><br>";
            echo "<p align='left'><h2><font color='red'>Oops! Only Letters and Numbers are allowed on the User ID portion.</font></h2><br><br>Please <a href='javascript:onClick=history.go(-1)' class='divProfile'>&raquo; GO BACK &laquo;</a> and remove any spaces and special characters.</p>";
            exit();
        }
 
        $i++;
}

[TheServant]

Thanks for your input, and welcome to Bytes. I think that rather than forbidding every character possible (black-list) it would be better to have a white-list of allowed characters. Also, what about people with hyphenated names?

[hsriat]

@exoskeleton
If you are talking about HTML special characters, then just do...

if (htmlspecialchars($string) != $string) {
//it contains special chars.
}

[Markus]

@TheServant
Furthermore, that loop is completely unnecessary. Using preg_match() you can do that in 1 line of code.

[TheServant]

@hsriat
hsriat, I think the OP is long gone, this is a very old post that has been dug up and put at the top of the list :(

Furthermore, that loop is completely unnecessary. Using preg_match() you can do that in 1 line of code.

Amen.

[RodanMedia]

@hsriat
I'll have to give this a shot, but I'm facing a deadline here. So this will be an improvement over our beta version - but later. In the meantime, for all of you, I appreciate your input. Unfortunately, I tried a preg_match() and couldn't make it work, and there's no time to piddle with it. What the code does is verifies a userID, then if there are no special characters, and all other fields are inserted properly, establishes a series of database tables, named after the userID, in SQL. This may be a regurgitated thread, but it came in handy when I needed it. We launch our social network site October 12. There's just no time to become a PHP expert in that time frame.

Now, if I could still program that old Sperry in COBOL ... oh, well.

[RodanMedia]

I should add, the user setting up their account determines their userID ... and we're not converting anything in the userID field, it simply becomes the name of several new database tables. Hence, we must forbid certain characters that can't be included in a data-table name.

[TheServant]

You don't have to be an expert to use preg_match. Try this:

if ( ! preg_match(/^[a-zA-Z0-9]+$/", $userID) ) {
// Display error
}

I think that will do all your code does, plus cover EVERY character other than letters and numbers.

[RodanMedia]

Thank you! I'll plug this in and run a test. The other code is already live, but this can quickly take its place. I sure picked the wrong week to start learning PHP - LOL!

[TheServant]

No worries, let us know if you have any problems.