2
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I need some improvements on my code. I did some validation by preg_match and functions. I need some special characters restrictions every field.

<?php
$error='';
if(isset($_POST['submit']))
{
if(nameField($_POST['name'])=='')
{
    $error="Invalid Name";
}

if(numberField($_POST['phone'])=='')
{
    $error.="<br>Invalid Number";
}
if(nameField($_POST['address'])=='')
{
    $error.="Invalid Address";
}
if($error)
{
    echo $error;
}
else
{
    echo "Form submitted successfully";
}
}

function nameField($val)
{
if(preg_match("/([%\$#\*\'\"\()]+)/", $val)) //Not allowed some of the special characters
{
return false;
}
else
{
return true;
}
}
function numberField($val)
{
if(preg_match("/^[0-9]*$/", $val))
{
return true;
}
else
{
return false;
}
}
?>

<html>
<body>
<form method="post">
<input type="text" name="name"/>
<input type="text" name="phone">
<input type="text" name="address">
<input type="text" name="city">
<input type="submit" name="submit" value="Submit"/>
</form>
</body>
</html>
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3
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I'll try to keep things brief, for a change:

nameField seems reasonable enough. Although I do have some suggestions (see below).
The numberField function is another matter. If you want to check for a valid phone number, there are a couple of things to consider:

  • User tend to enter a phone number in a human-readable format: 213-1234-4454 or 123/1234.4567
  • International phone numbers can start with Either a double 0, or a plus sign. both of which are valid: (0012) 123/1234-5678 is a possible value you'd have to process, just as +12 123/1234-5678

Bottom line: First trim the non-numeric chars, then check if the input is valid, I'd say:

function sanitizeAndValidate($phoneNr)
{
    //replace all non-numeric chars, after replacing a single + char with 00
    $phone = preg_replace('/[^\d]/', '', str_replace('+', '00', $phone, 1));
    $len = strlen($phone);
    //perhaps changing these constants to argumenst might be preferable
    if (is_numeric($phone) && $len >= MIN_PHONE_LEN && $len <= MAX_PHONE_LEN)
        throw new \InvalidArgumentException(
            sprintf(
                '%s is an invalid phone number (%s after sanitation)',
                $phoneNr,
                $phone
            )
        );
    return $phone;

}

Pas the raw phone number to this function, if the phone number is valid, you'll get a santized version back. If the phone number is invalid, catch the exception and present the user with an error message.

The nameField function is OK, but it's a bit redundant. If you only use it in one place, I'd avoid the overhead of a function-call, and simply inline the check, by replacing if (nameField($_POST['name'])) with this:

if (preg_match('/([%_\$#*\'"\()]+)/', $_POST['name']))

You might have noticed that I don't escape all of the chars, simply because there's no reason to escape them all. I've also added _ to the restricted chars. Simply because everybody knows that % is a MySQL wildcard, but not everybody seems to be aware that _ is, too.

Regular expressions can impact preformance, which is, I suspect, why you're asking for ways to improve your code. An alternative to preg_match here could be to have an array of prohibited chars, and use str_replace:

$notAllowed = array('%', '_', '$', '#', ...);//and so on
if (str_replace($notAllowed, '', $_POST['name']) !== $_POST['name'])
{//values are not the same, a forbidden char was replaced
    //name contains prohibited char
}

I'm not so sure if that would be faster then a preg_match, though, and besides: premature optimization is the root of all evil.

Last comment:
Please, try to adhere to the coding standards as much as possible. You seem to have some formatting issues

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  • \$\begingroup\$ Thanks for your suggestion. The nameField() I've to use more times and other pages also. \$\endgroup\$ – PNG Aug 13 '14 at 13:17
  • \$\begingroup\$ @Prakash: In that case, keep the function, but make sure that str_replace isn't the faster option. Also simplify it a bit: write function nameField($n) { return preg_match('/<your regex>/', $n); } instead of the if-else business. It'll return what illegal char was found, which could be useful \$\endgroup\$ – Elias Van Ootegem Aug 13 '14 at 13:47
2
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  • Please, please, please indent your code.

  • HTML5 includes <input type="tel" /> for phone numbers, though it's currently unsupported by the major browsers. You can choose whether or not you want to use this; it'll just default to a text field.

  • There is no point in using if (condition) return true; else return false;. Ever. Instead, just write:

    return preg_match('/^[0-9]*$/');
    
  • You could name numberField better; the function name should include a verb. Furthermore, do you really mean to match empty string? If not, use + instead of *.

  • Your use of $error is inconsistent. I propose using an array instead:

    $errors = array();
    if (nameField...) {
        $errors[] = "Invalid Name";
    }
    if (numberField...) {
        $errors[] = "Invalid Number";
    }
    ...
    echo $errors ? implode("<br />", errors) : "Form submitted successfully";
    
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