PHP mktime没有按预期工作

Question

With my code I'm trying to make the URL go to the previous or next month on a button click based on what is in the current URL.

For example if I have the end of the URL as index?view=list&month=January&year=2014 then I would want the previous button to go to index?view=list&month=December&year=2013. For January it works fine, but when the month is February the previous button equals February and the next button is April.

Previous Button

onclick="location.href='?view=list

&month=<?php echo date("F", mktime(0, 0, 0, date('n', strtotime($_GET['month'])) - 1, 1, $_GET['year'])); ?>

&year=<?php echo date("Y", mktime(0, 0, 0, date('n', strtotime($_GET['month'])) - 1, 1, $_GET['year'])); ?>

Next Button

onclick="location.href='?view=list

&month=<?php echo date("F", mktime(0, 0, 0, date('n', strtotime($_GET['month'])) + 1, 1, $_GET['year'])); ?>

&year=<?php echo date("Y", mktime(0, 0, 0, date('n', strtotime($_GET['month'])) + 1, 1, $_GET['year'])); ?>

Answer 1

This code may work smoother for you. It makes use of the strtotime's ability to move the date forward or backward:

Previous button:

onclick="location.href='?view=list

&month=<?php echo date('F', strtotime($_GET['month'].' '.$_GET['year'].' -1 month')); ?>

&year=<?php echo date('Y', strtotime($_GET['month'].' '.$_GET['year'].' -1 month')); ?>

Next button:

onclick="location.href='?view=list

&month=<?php echo date('F', strtotime($_GET['month'].' '.$_GET['year'].' +1 month')); ?>

&year=<?php echo date('Y', strtotime($_GET['month'].' '.$_GET['year'].' +1 month')); ?>