Php no special characters allowed

I have a simple registration script I'm practicing with and I was wondering how I could check for special characters and numbers. Basically, for the user name area, no special characters are allowed. For the first name , last name area, no special characters and numbers are allowed. Would this be a regex operation?

asked Jul 27, 2011 at 18:29

1

When I post information to php from a form I like to use the ctype functions, its what they are for. //php.net/manual/en/book.ctype.php

So if you wanted to a-zA-Z you could

if[ !ctype_alpha[ $str ] ]
   die[ 'Invalid characters' ];

Or if you wanted a-zA-Z0-9 you could

if[ !ctype_alnum[ $str ] ]
   die[ 'Invalid characters' ];

answered Jul 27, 2011 at 18:40

Matt R. WilsonMatt R. Wilson

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1

$stringWithout = preg_replace['/[^a-zA-Z]/', '', $string];
$stringWith = $string;
if [$stringWith == $stringWithout] {
    //string is clean
}

Something like this perhaps? If you replace every character but a-z and A-Z with nothing, and compare them, then if they are the same, you will know what they typed in has to be only characters like a-z and A-Z.

And yes, this uses a regex to replace the characters.

answered Jul 27, 2011 at 18:34

SteveSteve

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Don't try to reject stuff you don't want - you'll always find out later that users are much more imaginative than you.

Only accept what you know you can handle. If you only want latin letters and spaces, validate that that is the only thing you're getting with something like:

/^[0-9a-zA-Z ]+$/

Add only the characters you trust in there if I missed some.

answered Jul 27, 2011 at 18:34

MatMat

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I am using preg_match for restrict the special characters in form post. Now I need to restrict some special characters only like %,$,#,* and I need to post like bé. How to possible to restrict some special characters only.

My code:

asked Aug 13, 2014 at 8:29

2

You should use:

[[%\$#\*]+]

to match those characters.

So in preg_match you should use:

if[preg_match["/[[%\$#\*]+]/", $firstname]]
{
   echo 'Invalid Name';
}
else
{
   echo $firstname;
}

β.εηοιτ.βε

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answered Aug 13, 2014 at 8:32

Marcin NabiałekMarcin Nabiałek

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3

Blacklisting [=enumerating invalid characters] is not an option in the unicode world. Consider for example, a "name" like this:

Ж☝ⓚƒ

You don't really want to blacklist all of these.

A whitelisting approach is, on the contrary, quite simple using the u mode and unicode properties:

var_dump[preg_match['/^[\p{L}\p{N}]+$/u', 'ßäßå']];  // 1
var_dump[preg_match['/^[\p{L}\p{N}]+$/u', 'r2d2']];  // 1
var_dump[preg_match['/^[\p{L}\p{N}]+$/u', 'w#t?']];  // 0
var_dump[preg_match['/^[\p{L}\p{N}]+$/u', 'Ж☝ⓚƒ']];  // 0

And since we're talking about validating real names, please read Falsehoods Programmers Believe About Names before you start complicating things.

answered Aug 13, 2014 at 8:32

georggeorg

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4

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