php calendar previous button continuously incrementing - php

Question

"Thank you I have already solved my problem I think this one work"
I have a code that display only mondays of the month.
The next button is not calculating well.
Supposed to be it well end on 12(Month).
But it continuously adding the month.
This is my PHP code.
<?php
$current_month = date("n");
$month = ($_GET['m']) ? $_GET['m'] : date("n");
$previous_month = ($month - 1);
$next_month = ($month + 1);
$year = ($_GET['y']) ? $_GET['y'] : date("Y");
$previous_year = $year;
if($month == 0)
{
$month = 12;
$year--;
}
if($month == 13)
{
$month = 1;
$year++;
}
if($previous_month == 0)
{
$previous_month = 12;
$previous_year--;
}
$startDate = $year."-".$month."-01";
$endDate = $year."-".$month."-31";
$endDate = strtotime($endDate);
echo("<form name = 'formCalendar' id = 'formCalendar' action = 'calendar1.php?' method = 'get'>");
echo '<table border=1>';
echo '<tr>';
for($i = strtotime('Monday', strtotime($startDate)); $i <= $endDate; $i = strtotime('+1 week', $i))
echo '<td>'.date('d-M-y', $i).'</td>';
echo '</tr>';
echo(" </select>");
echo(" <input type = 'button' name = 'prev' value = '<<' onclick = 'location=\"calendar1.php?m={$previous_month}&y={$previous_year}\"'/>");
echo(" <input type = 'button' name = 'next' value = '>>' onclick = 'location=\"calendar1.php?m=". ($month + 1)."&y={$year}\"'/>");
echo(" </table>");
echo("<form>");
?>
Pls help fix the problem.

Answer 1

here is your complete working code
<?php
$current_month = date("n");
$month = (isset($_GET['m'])) ? $_GET['m'] : date("n");
$year = (isset($_GET['y'])) ? $_GET['y'] : date("Y");
$previous_month = ($month - 1);
$next_month = ($month + 1);
$previous_year = $year;
$next_year = $year;
if($previous_month==0)
{
$previous_month = 12;
$previous_year = $year-1;
}
if($next_month>12)
{
$next_month = 1;
$next_year = $year+1;
}
$startDate = $year."-".$month."-01";
$endDate = $year."-".$month."-31";
$endDate = strtotime($endDate);
echo("<form name = 'formCalendar' id = 'formCalendar' action = 'calender1.php?' method = 'get'>");
echo '<table border=1>';
echo '<tr>';
for($i = strtotime('Monday', strtotime($startDate)); $i <= $endDate; $i = strtotime('+1 week', $i))
echo '<td>'.date('d-M-y', $i).'</td>';
echo '</tr>';
echo(" </select>");
echo(" <input type = 'button' name = 'prev' value = '<<' onclick = 'location=\"calender1.php?m={$previous_month}&y={$previous_year}\"'/>");
echo(" <input type = 'button' name = 'next' value = '>>' onclick = 'location=\"calender1.php?m={$next_month}&y={$next_year}\"'/>");
echo(" </table>");
echo("<form>");
?>

Answer 2

Try this:
if ($month == 12) {
$previous_month = $month;
$next_month = 1;
} else {
$previous_month = ($month - 1);
$next_month = ($month + 1);
}
That solves the month issue

Answer 3

This question maybe little old post but I hope it helps to finetune the answer especially on the month issue when cross over the year
$previous_month = date("m", strtotime("-1 month", $year."-".$month."-01"));
$next_month = date("m", strtotime("+1 month", $year."-".$month."-01"));