error Undefined offset while using explode - php

Question

$a = explode(",",$data['ids'][$i]);
$dbtvalues = array();
for($j=0;$j< count($a);$j++)
{
$dbtvalues['serial_no'] =$a[$j];
if($data['modelno'] !="select")
{
$dbtvalues['model_no'] = $data['modelno'][$j];
}
$dbtvalues['indent_detail_id1'] = (int)$last_id ;
$data['indent_req_detail_id'][$i];
$this->outpatient_model->insert_row('tra_indent_issue_detail',$dbtvalues);
}
$a need to explode and insert into db if array has 5 values 5 rows must be inserted into table.
getting error message as :
Severity: Notice
Message: Undefined offset: 2
Filename: controllers/indent_receipt.php
Line Number: 71
A PHP Error was encountered
Severity: Notice
Message: Undefined offset: 3
Filename: controllers/indent_receipt.php
Line Number: 71
A PHP Error was encountered
Severity: Notice
Message: Undefined offset: 4
Filename: controllers/indent_receipt.php
Line Number: 71
A PHP Error was encountered
Severity: Notice
Message: Undefined offset: 5
Filename: controllers/indent_receipt.php
Line Number: 71
A PHP Error was encountered
Severity: Notice
Message: Undefined offset: 2
Filename: controllers/indent_receipt.php
Line Number: 71
thanks in advance.

Answer 1

Index is not exists. that why warning occurs
$a=array();
if(!empty($data['ids'][$i]))
$a = explode(",",$data['ids'][$i]);
Put above if condition it's working when index is not empty.