a – “am” or “pm”
A – “AM” or “PM”
d – date，from “01″ to “31″
j – date, from “1″ to “31″
D – Day of the week，from “Sun” to “Sat”
l – Day of the week，from “Sunday” to “Saturday”
w – day of the week, from “0″ to “6″
F – month，from “January” to “December”
M – month, from “Jan” to “Dec”
m – month, from “01″ to “12″
n – month, from “1″ to “12″
g – 12-hour clock. from “1″ to 12″
h – 12-hour clock. from “01″ to “12″
G – 24-hour clock. from “0″ to “23″
H – 24-hour clock. from “00″ to “23″
i – minute, from “00″ to “59″
s – second, from “00″ to “59″
U – total seconds
S – add English ordinal, such as “th”, ”nd”
t – set the day of the month, such as “28″ or “31″
z – set the day of the year, from “0″ to “365″
Y – year, such as “2010″
y – such as “10″