Adding to months in array - php

Question

Hi I've created an array where I increment "25/11/2015" by 1 month. I have a question about how it is working. I'm currently using "strtotime('+1 month', $currentdate)". I was wondering why in my first row of the array +1month isn't added straight away. Instead I am left with NOV-15 which is what I want but I was just wondering why this happens.
currently I'm getting:
Nov-15
Dec-15
Jan-16
why am i not outputting this result:
Dec-15
Jan-16
Feb-16
Heres my code:
$date = "2015-11-25";
$start = strtotime($date);
$currentdate = $start;
$times_table = array();
for($i = 0; $i <= 3; $i++){
$times_table[$i] = array();
}
echo "<pre>";
for($i = 0; $i <= 3; $i++){
for($j = 0; $j <= 4; $j++){
if ($j == 0){
$times_table[$i][$j]= "Version 5" ;
}
else if ($j == 1){
$cur_date = date("M-y", $currentdate);
$currentdate = strtotime('+1 month', $currentdate);
$times_table[$i][$j]= $cur_date ;
echo $cur_date . ">". "<br />";
}
else{
$times_table[$i][$j]= "gary" ;
}
if ($j == 3) {
$numbers = mt_rand(1, 100);
$times_table[$i][$j]= $numbers ;
}
if ($j == 4){
if($i == 0 || $i == 3)
{
$pay = "P";
$times_table[$i][$j]= $pay ;
}
else{
$int = "I";
$times_table[$i][$j]= $int ;
}
}
}
}

Answer 1

What you write is what you get:
$cur_date = date("M-y", $currentdate);
$currentdate = strtotime('+1 month', $currentdate);
$times_table[$i][$j]= $cur_date ;
You set the $currentdate value to $cur_date before one month was added, and then store the $cur_date value. This is the reason why it doesnt add 1 month straight away (it is added straight away to $currentdate but not to $cur_date)