PHP

Insert timing examples, esp. for testing code.

year

date('Y') 4 digit year : 2021

date('y') 2 digit year : 21

month

date('M') short name of month : Oct

date('F') full name of month : October

date('m') number of month (01..12) : 10

date('n') numeric month (1..12) : 10

date('t') number of days in current month: 31

week

date('W') week in year : 43

days

date('D') short name of day : Mon

date('l') full name of day : Monday

date('w') numeric day in week (0..6) : 1

date('d') day in month : 25

date('S') 2 char ordinal suffix for day : th

date('z') numeric day in year (0..364): 297

time

date('H:i') 24-hour time : 23:36

date('U') UNIX timestamp : 1635204989

getdate()

[seconds] 29

[minutes] 36

[hours] 23

[mday] 25

[wday] 1

[mon] 10

[year] 2021

[yday] 297

[weekday] Monday

[month] October

[0] 1635204989 (UNIX timestamp)

date('Y-m-d') 2021-10-25

date('m-d-y') 10-25-21

date('M. d, Y') Oct. 25, 2021

date('l, \t\h\e jS \o\f F') Monday, the 25th of October
NOTE — single quotes prevent PHP from turning \t and \f into TAB and FF

date & getdate can format other dates
IF they're converted to timestamps

mktime( h, min, sec, mon, d, yr )
creates a timestamp — a date in seconds since the epoch, 1-1-1970

find the date, 18 days from now

Create timestamp for 18 days from now.

$plus18d = mktime( 0, 0, 0, date('m'), date('d') +18, date('Y') );

date('l, M-d-Y',$plus18d) Friday, Nov-12-2021

getdate( $plus18d ) array for 11-12-2021

find day of week 1 year ago

$minus1yr = mktime( 0, 0, 0, date('m'), date('d'), date('Y')-1 )

date('l, M-d-Y',$minus1yr) Sunday, Oct-25-2020

week boundaries

Create timestamp for current Sunday (day in month (25) - numeric weekday (1)) :

$curr_sunday= mktime( 0, 0, 0, date('m'), date('d')-date('w'), date('Y') );

Create timestamp based on current Sunday plus 7 days :

$next_sunday = mktime( 0, 0, 0, date('m',$curr_sunday), date('d',$curr_sunday)+7, date('Y',$curr_sunday) )

DAY-LIGHT SAVINGS / STANDARD TIME!

Don't calculate a week as 604800 seconds — twice a year it will be wrong.

BAD: $next_sunday = $curr_sunday + 604800; (use mktime() above)