strftime gets wrong date

Question

I'm using strftime to display future date.

But while using

strftime('%a., %d. %B %Y',time()+60*60*24*4)

I'm getting Mo., 01. April 2013 instead of Su., 31. March 2013 while using this today.

(Unix timestamp is 1364423120)

strftime('%a., %d. %B %Y',time()+60*60*24*3)

displays the correct Sa., 30. March 2013

What is wrong here with the last day of March?

Answer 1

The timestamp represents 23:25:20 local time. As daylight savings time comes into effect on March 31th, adding 96 h will give 00:25:20 as local time, thus a date one day later than expected. Using gmstrftime instead of strftime avoids this problem.

<?php

$timestamp = 1364423120;

echo strftime('%a., %d. %B %Y (%c %Z)', $timestamp)."\n";
echo strftime('%a., %d. %B %Y (%c %Z)', $timestamp +60*60*24*4)."\n";
echo gmstrftime('%a., %d. %B %Y (%c %Z)', $timestamp)."\n";
echo gmstrftime('%a., %d. %B %Y (%c %Z)', $timestamp +60*60*24*4)."\n";

gives

Wed., 27. March 2013 (Wed Mar 27 23:25:20 2013 CET)
Mon., 01. April 2013 (Mon Apr  1 00:25:20 2013 CEST)
Wed., 27. March 2013 (Wed Mar 27 22:25:20 2013 GMT)
Sun., 31. March 2013 (Sun Mar 31 22:25:20 2013 GMT)