I spot (($year)%4). That's incomplete. Every year divisible by 4 is a leap except those divisible by 100. But those divisible by 400 are also leap years. 

2095 n
2096 y
2097 n
2098 n
2099 n
2100 n <-- %100==0
2101 n
2102 n
2103 n
2104 y
2105 n

1995 n
1996 y
1997 n
1998 n
1999 n
2000 y <-- %400==0
2001 n

[download]

But since you're restricting yourself to the years 1970 to 2038, you're ok.

You've basically reimplemented (core module) Time::Local's timegm_nocheck, so you might want to verify against it.

In reply to Re: high speed/efficiency http date to unix time, leap years handling? by ikegami
in thread high speed/efficiency http date to unix time, leap years handling? by bulk88

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.