Debug simple php while code - php

Question

I am getting this error: "Fatal error: Can't use function return value in write context in D:\Programas\wamp\www\away\index.php on line 18". Line 18 being the if statement.
Can anyone help me out on this? Thanks.
$vars = array("first_date_month", "first_date_day", "last_date_month", "last_date_day", "resume_date_month", "resume_date_day", "pay_date_month", "pay_date_day", "pay_time_hour", "pay_time_minutes");
$err_flag = false;
$i = 0;
while ($i < count($vars) and $err_flag == false)
{
if ( (!isset($_GET($vars[$i])) or ($_GET[$vars[$i] == "0") )
$err_flag = true;
$i++;
}

Answer 1

Maybe I'm not seeing well, but:
if ( (!isset($_GET($vars[$i])) or ($_GET[$vars[$i] == "0") )
You got a really awful mixup of parenthesis and square brackets. There's no such thing as
$_GET()
Big typo you have to correct.

Answer 2

Your code is a mess.
$_GET is an associative array and not a function (you are using the function call syntax passing $vars[$i] as an argument). In the second $_GET there's one ] missing.
Line 18 should be:
if ( (!isset($_GET[$vars[$i]]) or ($_GET[$vars[$i]] == "0") )

Answer 3

My take at it:
$vars = array("first_date_month", "first_date_day", "last_date_month", "last_date_day", "resume_date_month", "resume_date_day", "pay_date_month", "pay_date_day", "pay_time_hour", "pay_time_minutes");
foreach ($vars as $var) {
if ($err_flag = empty($_GET[$var]))
break;
}
8)
I assume the marked answer has... well.. answered the problems in your code, so just throwing out some optimizations:
using foreach() instead of while/for
is simple in many cases where we are
just iterating over an array - we can get the value and also the key if needed.
using the empty() function (returns true for anything null, false, 0, "", "0")
exit the loop when you're done using break

Answer 4

$_GET is a variable, an array -- and not a function.
It means you have to use array-access, with [], to get the data it contains.
So :
$_GET[$vars[$i]]
instead of
$_GET($vars[$i])
for the first time you are using $_GET.
And, for the second time, you forgot to close one ] ; which means you need to use :
$_GET[$vars[$i]]
instead of
$_GET[$vars[$i]
In the end, you while-loop should look like this :
while ($i < count($vars) and $err_flag == false)
{
if ( !isset($_GET[$vars[$i]]) or $_GET[$vars[$i]] == "0" ) {
$err_flag = true;
}
$i++;
}
Note I also added {} arround the body of the if condition ; this way, if you ever have to add something, you won't risk forgetting those ;-)

Answer 5

Change your line 18 if... to:
if ( (!isset($vars[$i])) or ($vars[$i] == "0") )
$err_flag = true;
$i++;
This mainly because I -and this is purely personal, I suspect- don't like using the $_GET[...] throughout the script; assign:
$variable_from_GET[] = $_GET['variable_name'];
and then use the $variable_from_GET array variable in your conditions which you -I presume- you did since you had a $vars array.