PHP for loop error Undefined offset

Question

I have the code below which loops through selected checkboxes and executes and sql statement.

if (isset($_POST['delete']))
{
   for($i=0;$i<$recordcount;$i++)                       
   {                        
       $deleteid = isset($_POST['checkbox'][$i]);
       echo "ID = ".$deleteid."<br />"; //Error checking
       $sqldelete = "DELETE FROM customer WHERE cus_ID = ".$deleteid."";
       echo $sqldelete."<br />"; //Error checking
       $deleters = $conn->Execute($sqldelete);                  
   }
}

This runs the sql query but it tries it run it once more than required, i.e I check two check boxes, the sql runs 3times. So this casues an error as the ID is empty. I also get an undefined offset 1.

Any advice? Thanks.

$recordcount is the amount of rows returned from SQL select statement. — Elliott
– Elliott, Commented Dec 8, 2010 at 12:11
isset() will return a boolean true or false in $deleteid, is that really what you want? — Mark Baker
– Mark Baker, Commented Dec 8, 2010 at 12:11
I want to check if the button 'delete' is pressed, the code works but the sql statements tries to execute one more than required. — Elliott
– Elliott, Commented Dec 8, 2010 at 12:12
The code doesn't work correctly: it will always try to delete cus_IDs 0 and 1, because the $deleteid boolean will be cast to 0 or 1 from false or true — Mark Baker
– Mark Baker, Commented Dec 8, 2010 at 12:15

Jon · Accepted Answer · 2010-12-08 12:12:35Z

3

This line is definitely wrong:

$deleteid = isset($_POST['checkbox'][$i]);

Maybe you meant it like this?

$deleteid = isset($_POST['checkbox'][$i]) 
    ? intval($_POST['checkbox'][$i]) : false;
if ($deleteid === false) {
    continue;
}

// rest of the code follows

Also, you could probably get rid of $recordcount and do a foreach over $_POST['checkbox'].

answered Dec 8, 2010 at 12:12

Jon

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Comments

Mark Baker · Accepted Answer · 2010-12-08 12:12:44Z

2

if (isset($_POST['delete']))
{
   for($i=0;$i<$recordcount;$i++)                       
   {                        
       $deleteid = isset($_POST['checkbox'][$i]);
       if ($deleteid) {
          $sqldelete = "DELETE FROM customer WHERE cus_ID = ".$_POST['checkbox'][$i];
          echo $sqldelete."<br />"; //Error checking
          $deleters = $conn->Execute($sqldelete);                  
       }
   }
}

And escape your input for safety

answered Dec 8, 2010 at 12:12

Mark Baker

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Comments

Bhanu Prakash Pandey · Accepted Answer · 2010-12-08 12:13:36Z

0

try this

if(isset($_POST['delete']))
    {
       $i=0;
        foreach($_POST['checkbox'] as $user)
        {
            $sqldelete = "DELETE FROM customer WHERE cus_ID = ".$user."";
           echo $sqldelete."<br />"; //Error checking
         $deleters = $conn->Execute($sqldelete); 
            $i++;
        }

    }

answered Dec 8, 2010 at 12:13

Bhanu Prakash Pandey

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