UTC time to sort

Each region has its own local time, on the Internet as well as radio communication in the time conversion problem is particularly prominent. I myself often confused here, specifically to study a little, recorded here in the memo. 

The whole earth is divided into 24:00 zones, each with its own local time zone time. In the case of international radio communications, for the sake of consistency, the use of a single time, when called Universal Coordinated (UTC, Universal Time Coordinated). The average time (GMT, Greenwich Mean Time) UTC and Greenwich, as are the same as the local London. Herein, UTC GMT with identical meaning. 

Beijing time zone is east eight districts, leading UTC eight hours in the e-mail header is recorded as +0800 Date field. If there is such a line in the header of the email: 

a Date: Fri, 08 Nov 2002 09:42:22 +0800 

Description local time to send the letter is two ○○ Ernian Shiyi Yue Bahao, Friday, nine in the morning point 4.42 (twenty-two seconds) ahead of UTC eight hours (+0800, is the East eight districts time) when a local this place. Date domain of the email header using twenty-four hour clock, instead of using the AM and PM to mark the afternoon. 

Time to send this e-mail, for example, if we want this time into UTC, using what formula: 

area = poor local time UTC + 

time zone difference is positive East and West is negative. Here, the Eastern time zone difference eight districts recorded as +0800, 

UTC + (+0800) = local (Beijing) Time (1) 

So, UTC = local time (Beijing time)) --0800 (2) 

0942--0800 = 0142 

That day is UTC 1:42:22. If the result is negative it means that the former UTC day, this time is a negative number plus 2400 UTC the previous day. For example, local (Beijing) time is 0432 (four thirty-two), then, UTC is 0432--0800 = -0368, negative sign means that the day before, -0368 + 2400 = 2032, both the night before eight thirty-two. 

West New York time zone is five areas, five hours behind UTC ratio, denoted by -0500: 

UTC + (-0500) = New York time (3) 

UTC + 0500 = New York time (4) 

to (2) - (4) compared style, 

UTC = GMT --0800 New York time = + 0500 (5) 

that is New York time = GMT + 1300 (6) 

Beijing time thirteen hours ahead of New York time from (6), 

New York time = Beijing time --1 300 (7) 

when in late April, New York and switch to daylight saving time, also known as daylight saving than the standard one hour ahead of New York time, actually become the standard time in four districts of the West, became -0400. 

UTC + (-0400) = New York daylight saving time, apply the above formula, 

GMT + 1200 = New York Summer Time 

= GMT Daylight Saving Time in New York --1200 

in these conversions, the most important formula is 

UTC + time zone difference between local time = 

Eastern time zone difference is positive, west negative. For example, the East eight districts (Beijing) is +0800, West Fifth District (New York) is -0500, California is eight districts in the West, is -0800, US Central time zone is six West District, -0600, US Mountain time zone is west seven districts , -0700, the Pacific time zone is west eight districts, -0800, use daylight saving time in the summer, it became -0700. East Germany time zone is a zone, + 0100 summer becomes +0200. 

Most e-mail programs such as Outlook Express, when displaying the time, the computer program the first time converted into the local time to display, for example, e-mail Date field is: 

Date: Fri, 08 Nov 2002 09:42:22 +0800 

Outlook Express is displayed in the display: 

a Date: Thur, 07 Nov 2002 08:42:22 PM, the Beijing converted into New York time, and the twenty-four hours time format converted into twelve-hour format. Of course, in order to time the conversion right, time zone, sender and computers recipient must be set up correctly, here, the time zone of the sender to correctly set to Beijing time zones east eight districts, and my time zone to be set to West Fifth District