PHP - Help Me Understand This Operator

I'm having trouble understanding the behavior of Prefix decrementing operator VS. Postfix decrementing Operator

Postfix decrementing Operator
Code: [Select]
<?php

$a = 1;

$a = --$a + 1;

echo $a;

// this outputs 1

?>


VS....

Prefix decrementing operator
Code: [Select]
<?php

$a = 1;

$a = $a-- + 1;

echo $a;

// this outputs 2

?>

Hi

Ok, so I pick a random value 23 for example and I want this value to be in between two other values.
E.g. if 23 is in between 20 and 30, then continue otherwise die.

How can I do this?

I've been looking through the Joomla docs trying to understand how everything works and I've seen something that I don't understand and cannot find an answer to anywhere on the net.

The basic question is what is the ampersand used for in this conditional he

if (!($mask & 1) && is_string($var)) {

The two in the middle are obviously the AND part of the conditional.  I know it can be used for creating references to variables but I don't think this is what is happening here.  I've seen people using it to test for odd and even numbers too but with no explanation of how it works/what it does.  The full code is below:


function _cleanVar($var, $mask = 0, $type=null)
    {
        // Static input filters for specific settings
        static $noHtmlFilter    = null;
        static $safeHtmlFilter    = null;
 
        // If the no trim flag is not set, trim the variable
                if (!($mask & 1) && is_string($var)) {
            $var = trim($var);
        }
 
        // Now we handle input filtering
                if ($mask & 2)
        {
            // If the allow raw flag is set, do not modify the variable
                        $var = $var;
        }
        elseif ($mask & 4)
        {
            // If the allow html flag is set, apply a safe html filter to the variable
                        if (is_null($safeHtmlFilter)) {
                $safeHtmlFilter = & JFilterInput::getInstance(null, null, 1, 1);
            }
            $var = $safeHtmlFilter->clean($var, $type);
        }
        else
        {
            // Since no allow flags were set, we will apply the most strict filter to the variable
                        if (is_null($noHtmlFilter)) {
                $noHtmlFilter = & JFilterInput::getInstance(/* $tags, $attr, $tag_method, $attr_method, $xss_auto */);
            }
            $var = $noHtmlFilter->clean($var, $type);
        }
        return $var;
    }

Hi,

This ones stumped me a little as i've done this previously and it seemed to work fine:

I have a form to add with two password boxes, the IDs are different as they should be but the type is the same:

Code: [Select]
<form action="<?php echo $PHP_SELF;?>" method="post">
<p>New Password: <input type="password" id="newpassword" name="newpassword" /></p><br />
<p>Confirm Password: <input type="password" id="confirmpassword" name="confirmpassword" /></p><br />
<p><input type="submit" name="submit" value="submit"></p>
</form>

I have this code to check if they are both equal then md5 them and add them to the database:

Code: [Select]
// Check if button name "submit" is active, do this
if(isset($_POST['submit'])) {

//variable to identify user
$email = ($_SESSION['email']);

//post variable from form
$newpassword = $_POST['newpassword'];
$password = $_POST['confirmpassword'];

//if passwords are not equal
if($password != $confirmpassword)  { 
echo "The passwords do not match<br />"; 

//debugging - to see if they are equal or not - remove afterwards
echo $password . "<br />";
echo $newpassword . "<br />";
} 

//if passwords are equal
if($newpassword == $password)  {

//use md5 so they match when logging in
$password = md5($password); 
$newpassword = md5($newpassword);

$sql= "UPDATE users SET password='$newpassword' WHERE username='$email'"; 
$result = mysql_query($sql);
if($result) 
    { 
    echo "Congratulations You have successfully changed your password"; 
    }   
}
}

I've tried to explain my thinking as best i can in the code, the debugging part at the top shows that both values  seem to be identical yet i'm being thrown into the not equal loop and they aren't adding to the database.

Can anyone explain what i'm doing wrong here? I imagine its only minor but its thrown me.

Cheers

I see a couple people using the ? operator in php and was curious as to how it works?