PHP date, time-related knowledge collation

Unix Timestamp: The number of seconds elapsed from January 1, 1970 0 o'clock to the current time.

1. Convert a date to a Unix timestamp
Mktime (): can automatically correct out-of-bounds input

Prototype: Mktime (hour,minute,second,month,day,year);
Instance:

<?php    echo Date ("Y-m-d", Mktime (0,0,0,2,12,2015));   2015-12-12    echo Date ("Y-m-d h:i:s", Mktime (7,50,59,10,21,2015)),//2015-10-21 07:50:59    echo Date ("y-m-d", Mktime (0,0,0,12,33,2015));   2016-01-02, date more than 31 days, automatic correction time?>

2. Parse the date time of the English text into a UNIX timestamp
Strtotime ()
Prototype: Strtotime (Time,now)

<?php    Echo strtotime ("Now");   1447987573    echo Date ("Y-m-d", Strtotime ("Now");   2015-11-20    echo Date ("Y-m-d h:i:s", Strtotime ("Now");   2015-11-20 02:49:18    echo Date ("Y-m-d", Strtotime ("8 December"));   2015-12-08?>

Example: Writing a countdown program for anniversaries through Strtotime ()

<?php            $now = Strtotime ("Now");  Start time $endtime = Strtotime (' 2018-10-12 10:20:59 ');  Graduation time, turn into timestamp $second = $endTime-$now;   Gets the timestamp from graduation to present (number of seconds) $year = Floor ($second/3600/24/365);  The number of years calculated from this timestamp the floor   () function is rounded down to the nearest integer. $temp = $second-$year *365*24*3600;  Remove the number of seconds from the timestamp for the remainder of the month $month = Floor ($temp/3600/24/30);  Conversion Moon Number $temp = $temp-$month *30*24*3600;  Minus the number of seconds in the entire month, the number of seconds left for the number of days = Floor ($temp/3600/24);  Convert the remaining days $temp = $temp-$day *24*3600;  Minus the number of seconds in the day, the number of seconds left $hour = Floor ($temp/3600);  The number of hours remaining $temp = $temp-$hour *3600;  Minus the number of seconds in the whole hour, the number of seconds left $minute = Floor ($temp/60);  Calculate the remaining fraction $second1 = $temp-$minute *60;   Number of seconds left echo "distance graduated {$year} years {$month} month {$day} days {$hour} hours {$minute} minutes {$second 1} seconds";  2 years from graduation October 27 days 1 hours 56 minutes 14 seconds?>

Extension: Calculation of dates
The simplest way to calculate the distance between two dates is by calculating the two Unix timestamp only.
Example: To calculate the age of a user by receiving a birth date from an HTML form submission in a PHP script

<?php        $year = 1989; $month = n; $day =; $birthday = Mktime (0,0,0, $month, $day, $year);   Convert to Timestamp $nowday = Strtotime ("Now");  Gets the current datetime timestamp $ageunix = $nowDay-$birthday; $age = Floor ($ageUnix/(60*60*24*365)); echo "Age: $age";   Age:25?>

Date and time formatted output
The UNIX timestamp is used as the standard format when the date and time need to be saved or calculated.
Cons: Unix timestamp format is poor readability
Workaround: Call date () to format the local time and date
Syntax Date (format,timestamp) formatting a local time and date

<?php            date_default_timezone_set (' PRC ');//Set Chinese time zone echo date ("Y-M month-D Day H:i:s");   2015-November-20th 17:30:21    ?>

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Reference: "PHP in detail"

PHP date, time-related knowledge collation