unable to find error with array_merge - php

Question

I am trying to insert batch query in code igniter, I am not able to make array_merge work. Don't know whats the problem. M getting blank array.
$epin_amt = $this->input->post('amount');
$qty = $this->input->post('qty');
$data = array();
for ($i = 0; $i <= $qty; $i++) {
$array = array(
'epin' => mt_rand(100000, 999999),
'amount' => $epin_amt,
);
array_merge($data, $array);
}
print_r($data) ; // Produce : array( )

Answer 1

You have to assign the merged array back to your $data variable:
<?php
$epin_amt = /*$this->input->post('amount')*/ 5;
$qty = /*$this->input->post('qty')*/6;
$data = array();
for ($i = 0; $i <= $qty; $i++) {
$array = array(
'epin' => mt_rand(100000, 999999),
'amount' => $epin_amt,
);
$data = array_merge($data, $array);
}
print_r($data) ;

Answer 2

array_merge returns array. You need something like this:
$result = array_merge($data, $array);

Answer 3

You are merging the arrays but it's not done by reference so you're throwing the resulting array away. array_push() it instead, that will keep adding the arrays to your $data array:
<?php
$epin_amt = 10;
$qty = 20;
$data = array();
for ($i = 0; $i <= $qty; $i++) {
$array = array(
'epin' => mt_rand(100000, 999999),
'amount' => $epin_amt,
);
array_push($data, $array);
}
print_r($data) ;