How can I not allow certain characters?

[membot]

I want to be able to keep people from entering certain characters in a form. I've tried google, and had no luck so far. Thanks!

[kenrbnsn]

You can use Javascript to check the characters while the user is entering them. You can use PHP to check the data once the form has been submitted.

 

Ken

[membot]

I'd like to use PHP, since that's what I'm learning. Could you lead me to a certain function?

[Pikachu2000]

You can strip them out with str_replace().

[Anti-Moronic]

str_replace() won't suffice if you want to strip out many different 'types' of characters.

 

You can use preg_replace for that but you need to learn some basic regex. Here is what you are looking for:

 

http://www.phpro.org/tutorials/Validating-User-Input.html

 

this will strip out: (a,b,c,d,e):

 

$str = 'abq dadewcdefgh';

echo preg_replace("/[abcde]/", "", $str);

[Pikachu2000]

For the example you provided, str_replace() would be fine. There's no reason to use a regex when a string function will do the job.

[Anti-Moronic]

For the example you provided, str_replace() would be fine. There's no reason to use a regex when a string function will do the job.

 

Didn't realize - so do you mean use a series of str_replace to strip out each character? When would that become inefficient? How many characters say on a sample str size of 1000 characters?

 

Seems I need to delve more into the performance hit.

[Pikachu2000]

Not quite sure what you mean by 'use a series of str_replace', but this will perform the same task as the preg_replace above. Performance-wise, based on the average of 100,000 iterations, they're nearly identical.

$str = 'abq dadewcdefgh';
$repl = range( 'a', 'e');
echo str_replace($repl, '', $str);

[Anti-Moronic]

Not quite sure what you mean by 'use a series of str_replace', but this will perform the same task as the preg_replace above. Performance-wise, based on the average of 100,000 iterations, they're nearly identical.

$str = 'abq dadewcdefgh';
$repl = range( 'a', 'e');
echo str_replace($repl, '', $str);

 

Ahh, I see. Thanks! Very helpful.

[zane23snider]

As per my view PHP: is a widely used, general-purpose scripting language that was originally designed for web development to produce dynamic web pages.So can you tell me the best topic for my project which is very easy to develop and design.

[membot]

str_replace() will work great for me, thanks!