function error in job quizz

[BigBadKev]

Hi all,

here is a function that I was asked to fix for a quizz for a job interview, they replied saying I fixed 3/4 known errors but did not tell me what the fourth error is.

The errors I found
(1)return $check out of scope
(2)missing ";" at end of this line $check = ($s2 << 16) | $s1
(3)global $BASE not within function scope
(4)$query = $_GET['q'] needs a isset() to check if indeed it is set

Basically I made a class and ditched the function, by using class vars I got around $check and $BASE and of course the ";" was inserted but I am stumped on the other error? can you see it?

BBK

CODE BELOW EXACT AS THE QUIZZ

<?php
	global $BASE;
	$BASE = 65517;		// largest prime smaller than 65536

function check32($data) {
        $s1 = 1;
    $s2 = 0;
    for ($n = 0; $n < strlen($data); $n++) {
	$s1 = ($s1 + ord($data[$n])) % $BASE;
	$s2 = ($s2 + $s1) % $BASE;
    }
    $check = ($s2 << 16) | $s1
    return $check;
}

$query = $_GET['q'];
$check = check32($query);
echo "check value for the phrase \"$query\" is
$check";
?>

[devinemke]

the 4th error is pretty self-explanatory. what if someone hits this script without passing the "q" variable on the URL string? you will get a parse error on this line

$query = $_GET['q'];

you need to use the [man]isset[/man] function to make sure its there

[BigBadKev]

Hi devinemke,

I got that one

The errors I found
(1)...............
(2)...............
(3)...............
(4)$query = $_GET['q'] needs a isset() to check if indeed it is set

You must have missed this one, any other ideas? I am stumped

BBK

[LostMyLove]

you can also define q...

$q = '0'; and get method will redefine it...

[Weedpacket]

Your (1) is wrong, which is why you've counted four errors (the $check outside the function is a different variable to the one inside the function).

But the largest prime smaller than 65536 is 65521, not 65517 (which isn't even prime: it's a multiple of 3, which can be verified by adding its digits together).

[BigBadKev]

Hi Weedpacket,

Here is my actual code I submitted, I think its the prime number that got me, what do you think? (they were happy with my submission 🙂 ), and thanks for your help.

BBK

if (isset($_GET['q'])) {
  $calculate = new calculate;
  echo 'check value for the phrase ' . $_GET['q'] . ' is ' . $calculate->check32($_GET['q']);
}
else {
  echo "check value for a empty phrase is 1";
}

class calculate {

  var $s1;
  var $s2;
  var $base;
  var $check;

  function calculate() {
    $this->s1 = 1;
    $this->s2 = 0;
    $this->base = 65517;
    $this->check = NULL;
  }

  function check32($data) {
    $this->check = NULL;
    $length = strlen($data);
    for ($n = 0; $n < $length; $n++) {
      $this->s1 = ($this->s1 + ord($data[$n])) % $this->base;
      $this->s2 = ($this->s2 + $this->s1) % $this->base;
    }
    $this->check = ($this->s2 << 16) | $this->s1;
    return $this->check;
  }
}