PHP - Bitwise ~ Not W/ip2long() - 32 Bit Vs. 64 Bit Os?

could someone help me with this code? It works fine without ip2long function? weird
<form method="post" action="test.php"> 
<textarea name="new" cols="40" rows="10"> 
samplehost-1,127.0.0.1
samplehost-2,127.0.0.2
</textarea><br>
<input type="submit" value="Add Servers"> 
</form>
if(isset($_POST['new'])) {
$array= explode("\n",$_POST['new']);
foreach ($array as $ni) {
$array=explode(',', $ni);
echo ip2long($array[1]);
}
}

Hi every one,

I just want to know what is the use of '<<' and '>>' operators in php

So I have coded php for about 5-6 yrs and have never really needed to use binary conversions and the bitwise operator like >> or << .  I took a php class in college but that basically consisted of the students trying to learn php on their own...  So i have never had any exposure to that portion of php coding.  I have to take an exam on PHP with a bunch of questions that DO NOT show how good of a coder you are.  There are a bunch of questions on bitwise operators and binary conversions... Am I missing something???  Whats the point of converting a string to binary or knowing how to do this in your head?

Any help?

hi all,

I have an array(1,2,3,4) and

i make a form and make checkboxes for this array and user selects 2,3 and 4

when user submit form

then i save it in table by making selected check boxes and converting selected values into bitwise equivalent value

like this
                                       
                                       
foreach($data['meal_types'] as $v){
$mealTypeBits += pow(2,$v-1);
}


Now when i have to show user his selected data how will i compare table bitwise saved record with array(1,2,3,4) to get the values that he checked while saving.

Here is a simple script which uses bitwise operations to determine whether or not a checkbox has been set. The problem is that if you use the $alpha array, the script doesn't produce the results you should expect. For example, if you set the last checkbox while using the $alpha array, all the checkboxes become set.

I partially know why this happens as the PHP-Manual enlightened me:
Quote

From: http://www.php.net/manual/en/language.operators.bitwise.php
Don't right shift for more than 32 bits on 32 bits systems. Don't left shift in case it results to number longer than 32 bits.


I attempted to use the GMP_* functions but because those aren't part of the PHP-Standard-Library, I do not wish to rely on them. Is there any way to make these functions work for integers beyond 2^31?

Here is a standalone script I'm using to make these tests.

$alpha = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z');

$delta = range('a', 'z');

function generate($array){

$n = count($array);

$c = array();

for($i = 0; $i < $n; ++$i){

$c[bcpow(2, $i)] = $array[$i];

}

return $c;

}

function set($array, $post){

$c = 0;

foreach($array as $key => $val)

if(isset($post['c'.$key])) $c |= $key;

return $c;

}

function check($num, $category){

if($num & $category) return 'CHECKED';

return '';

}

function checkboxes($array, $numval=0){

$i = 0;

$form = '';

foreach($array as $key => $val){

$checked = check($numval, $key);

$form .= '<input type="checkbox" '.$checked.' name="c'.$key.'" id="c'.$key.'">' . '<label for="c'.$key.'"> '.$val.'</label><br />';

++$i;

}

return $form;

}

$array = generate($alpha);

$num = 0;

if(isset($_POST['action'])){

$num = set($array, $_POST);

echo $num;

}

echo '<form action="y.php" method="post" style="width: 400px; border: 1px solid black;">';

echo checkboxes($array, $num);

echo '<input type="submit" name="action" value="Set" />';

echo '</form>';