date function of PHP
date
(PHP 4, PHP 5)
date — Format a local time/date
初始化局部时间
Description
Returns a string formatted according to the given format string using the given integer timestamp or the current time if no timestamp is given. In other words, timestamp is optional and defaults to the value of time() .
返回指定的integer类型时间戳或者当前时间戳的格式化String，格式由format指定。换句话说，时间戳的默认值和time()函数一样。
format
The format of the outputted date string . See the formatting options below. There are also several predefined date constants that may be used instead, so for example DATE_RSS contains the format string 'D, d M Y H:i:s' .
根据格式输出时间String。可以看下列的格式符。当然，也有一些常量代表一些常用时间格式。比如说DATE_RSS就包含格式String ‘D, d M Y H:i:s’ 。
day
d Day of the month, 2 digits with leading zeros 01 to 31 一个月中天数，两位，不足补零。
D A textual representation of a day, three letters Mon through Sun 以三个字符表示星期几。
j Day of the month without leading zeros 一个月中天数，不补零。
l(lowercase 'L') A full textual representation of the day of the week Sunday through Saturday 完整表示星期几。
N ISO-8601 numeric representation of the day of the week (added in PHP 5.1.0) 1 (for Monday) through 7 (for Sunday) 以数字表示星期几（ISO-8601）
S English ordinal suffix for the day of the month, 2 characters st , nd , rd or th . Works well with j 以英语的序列数表示一个月中天数，两位，和j一样。
w Numeric representation of the day of the week 0 (for Sunday) through 6 (for Saturday) 以数字表示星期几（从0开始）。
z The day of the year (starting from 0) 0 through 365 一年中天数（从0开始）。
week
W ISO-8601 week number of year, weeks starting on Monday (added in PHP 4.1.0) Example: 42 (the 42nd week in the year) 以数字表示一年中第几个星期，一个星期以星期一开始。
month
F A full textual representation of a month, such as January or March January through December 一年中月份的完全表示。
m Numeric representation of a month, with leading zeros 01 through 12 一年中月份用数字两位表示，不足补零。
M A short textual representation of a month, three letters Jan through Dec 一年中月份的简略表示，三位。
n Numeric representation of a month, without leading zeros 1 through 12 一年中月份用数字表示，不补零。
t Number of days in the given month 28 through 31 给定的月份的天数。
year
F Whether it's a leap year 1 if it is a leap year, 0 otherwise. 闰年返回1，否则返回0。
o ISO-8601 year number. This has the same value as Y , except that if the ISO week number (W ) belongs to the previous or next year, that year is used instead. (added in PHP 5.1.0) Examples: 1999 or 2003 和Y功能相同，如果W的值在前一年和下一年，就用这一年的年份代替。
Y A full numeric representation of a year, 4 digits Examples: 1999 or 2003 以四位数字表示年份。
y A two digit representation of a year Examples: 99 or 03 以两位数字表示年份。
time
a Lowercase Ante meridiem and Post meridiem am or pm 小写的am和pm表示上午和中午。
A Uppercase Ante meridiem and Post meridiem AM or PM 大写的AM和PM表示上午和中午。
B Swatch Internet time 000 through 999 Swatch网络时间
g 12-hour format of an hour without leading zeros 1 through 12 12小时制表示时间，不补零。
G 24-hour format of an hour without leading zeros 0 through 23 24小时制表示时间，不补零。
h 12-hour format of an hour with leading zeros 01 through 12 12小时制表示时间，补零。、
H 24-hour format of an hour with leading zeros 0 through 23 24小时制表示时间，补零。
i Minutes with leading zeros 00 to 59 表示小时中分钟数，补零。
s Seconds, with leading zeros 00 through 59 表示秒数，补零。
u Microseconds (added in PHP 5.2.2) Example: 654321 微秒表示。
timezone
e Timezone identifier (added in PHP 5.1.0) Examples: UTC , GMT , Atlantic/Azores 时区标识符。
I(capital i) Whether or not the date is in daylight saving time 是否为夏令时，是返回1，不是0。
O Difference to Greenwich time (GMT) in hours Example: +0200 与GMT时区相差几个小时。
P Difference to Greenwich time (GMT) with colon between hours and minutes (added in PHP 5.1.3) Example: +02:00 与GMT时区相差多少小时分钟。冒号分隔小时和分钟。
T Timezone abbreviation Examples: EST , MDT ... 时区的缩写。
Z Timezone offset in seconds. The offset for timezones west of UTC is always negative, and for those east of UTC is always positive. -43200 through 50400 时区偏移的秒数，UTC以西为负数，以东为正数。
full date/time
c ISO 8601 date (added in PHP 5) 2004-02-12T15:19:21+00:00
r » RFC 2822 formatted date Example: Thu, 21 Dec 2000 16:01:07 +0200
U Seconds since the Unix Epoch (January 1 1970 00:00:00 GMT) See also time() Unix纪元（1970年）。