The document outlines various functions in PHP for handling date and time, including setting the timezone, formatting output, and calculating time differences. Key functions mentioned include date_default_timezone_set(), date(), time(), and strtotime(). It provides examples of how to use these functions to display the current date and time, as well as perform calculations involving past and future dates.

1. For date and time function we know first few things in our
mind
Date and time function
Capital S Year Day Month
Th,rd,st y—17 d=06 m=03
Example--1st Y—2017 n= 6 M=mar
l= Monday,tue.... F=march
D=Mon J=3

2. By using
[date_default_timezone_get();
using this function we can get the
time which is by default set.
date_default_timezone_set(“Asian/Calcutt
a”);
By using this function we can get the
current time of the current city or
country.

3. To set the time
 date_default_timezone_set(“Asian/Culcu
tta”);
 Echo date(“h:i:s a); date(h:i:s A);
 Date(h:i:p); date(h:i:s P);
 Am-anti mariadian
 Pm-post mariadian

4. Define the time
 G-24hr-1,2,3,4,5---------13,14,15,--------
22,23
 H-24hr-01,02,03,04,05----13,14,15------
22,23
 g-12hr-1,2,3,4,5,--------11,12,1,2,3,-------11
 h-12hr-01,02,03-----11,12,01,02,03-------11

5.  date_default_timezone_set(“Asian/Calcutta”)
;
 echo date(“d,l,F,y,g:i:s a”);
 Output- 06,Monday,March,17 10:58:06 am
Example

6. We also get output like below
 echo date(todayis l);
 Output---today is Monday
 echo “today is “.date(“l”);
 Output---today is Monday

7. echo time();
 By using this function we can get the number
of seconds and we can also call it as unix
timestamp. (1971-2017(or current time))
 echo (time()-1296000); 129600 is 15 days sec
 echo date(“y-m-d h:i:s a”,(time()-+1296000));
 o/p-17-02-19 11:10:50am (15 day back if -
1296000) or +1296000 then its (17-03-21
11:10:51)

8. Strtotime();
using this function we can get
the time of befor or after any
year (like 10 years ,20 years
before or after)
 strtotime(-10 years);
 strtotime(+20 years);

9. Example-difference between the date or years
 $birth=“1990-02-12”;
 $past=strtotime($birth);
 $curr=time();
 echo(($curr-$past)/(86400*365)); year
 86400 is seconds for a day
 echo(($curr-$past)/(86400*30)); month
 echo(($curr-$past)/(86400*7)); week