What causes: "Notice: Uninitialized string offset" to appear?

I have a form that users fill out, and on the form there are multiple identical fields, like "project name", "project date", "catagory", etc. Based on how many forms a user is submitting, my goal is to:

1. loop over the number of forms
2. create individual SQL insert statements

However, PHP throws me a NOTICE that I don't seem to understand:

Notice: > Notice: Uninitialized string offset: 1 ...dataPasser.php on line 90

PHP

$myQuery = array();
	
if ($varsCount != 0)
{
  for ($i=0; $i <= $varsCount; $i++)
  {
	$var = "insert into projectData values ('" . $catagory[$i] . "', '" .  $task[$i] . "', '" . $fullText[$i] . "', '" . $dueDate[$i] . "', null, '" . $empId[$i] ."')";
	array_push($myQuery, $var);		
  }
}

There are references to this issue I am having, but they are not exact and I am having trouble deducing where the actual problem stems from. I would greatly appreciate any help in understanding what is causing the array to not initialize properly.

This error would occur if any of the following variables were actually strings or null instead of arrays, in which case accessing them with an array syntax $var[$i] would be like trying to access a specific character in a string:

$catagory
$task
$fullText
$dueDate
$empId

In short, everything in your insert query.

Perhaps the $catagory variable is misspelled?

It means one of your arrays isn't actually an array.

By the way, your if check is unnecessary. If $varsCount is 0 the for loop won't execute anyway.

The error may occur when the number of times you iterate the array is greater than the actual size of the array. for example:

 $one="909";
 for($i=0;$i<10;$i++)
    echo ' '.$one[$i];

will show the error. first case u can take the mod of i.. for example

function mod($i,$length){
  $m = $i % $size;
  if ($m > $size)
  mod($m,$size)
  return $m;
}

for($i=0;$i<10;$i++)
{
  $k=mod($i,3);
  echo ' '.$one[$k];
}

or might be it not an array (maybe it was a value and you tried to access it like an array) for example:

$k = 2;
$k[0];

Try to test and initialize your arrays before you use them :

if( !isset($catagory[$i]) ) $catagory[$i] = '' ;
if( !isset($task[$i]) ) $task[$i] = '' ;
if( !isset($fullText[$i]) ) $fullText[$i] = '' ;
if( !isset($dueDate[$i]) ) $dueDate[$i] = '' ;
if( !isset($empId[$i]) ) $empId[$i] = '' ;

If $catagory[$i] doesn't exist, you create (Uninitialized) one ... that's all ; => PHP try to read on your table in the address $i, but at this address, there's nothing, this address doesn't exist => PHP return you a notice, and it put nothing to you string. So you code is not very clean, it takes you some resources that down you server's performance (just a very little).

Take care about your MySQL tables default values

if( !isset($dueDate[$i]) ) $dueDate[$i] = '0000-00-00 00:00:00' ;

or

if( !isset($dueDate[$i]) ) $dueDate[$i] = 'NULL' ;

Check out the contents of your array with

echo '<pre>' . print_r( $arr, TRUE ) . '</pre>';