Example introduction to PHP date function date format conversion_PHP tutorial

When developing websites, we often need to process dates and times. PHP provides many date and time functions to facilitate PHP developers to calculate and format dates and times. Therefore, it is very necessary to master PHP date functions, and it also lays the foundation for processing the format conversion between PHP date functions and Mysql database dates. Here we use PHP examples to introduce the basics of PHP: date function date and Unix timestamp function, as well as methods of converting date formats between each other.

PHP date and time zone setting

Before enabling the PHP date function, you first need to ensure that the set time zone is correct, otherwise the displayed date may be different. When setting up the PHP environment, you only need to set date.timezone to the corresponding time zone in the PHP.INI configuration file. If you do not have the right to operate the PHP.INI configuration file, you can obtain the time zone of the current PHP running environment through the PHP time zone function date_default_timezone_get(void), and then use the date_default_timezone_set(string $timezone_identifier) ​​function to set the corresponding time zone. More time zones supported by PHP You can check http://www.php.net/manual/en/timezones.php.

PHP format date function Date

Prototype string date(string $format[,int $timestamp])

$format - format code of PHP date function date
$timestamp - Unix timestamp, defaults to current timestamp (optional)

Format character———- Description———— Return value description

Day

1
d ——The day of the month, returns 2 digits ——01 to 31
2
j ——The day of the month, 1 to 9 without zero ——1 to 31
3
S - English suffix for the number of days in the month - 2 characters st, nd, rd or th. Can be used with j
4
z ——The day of the year ——0 to 366


Week

1
l —— day of the week ——Sunday to Saturday
2
D - English day of the week, text representation - 3 letters Mon to Sun
3
N - represents the day of the week as a number (new in PHP 5.1.0) - 1 (for Monday) to 7 (for Sunday)
4
w ——The day of the week ——0 (indicating Sunday) to 6 (indicating Saturday)
5
W - Week number in the year in ISO-8601 format, each week starts on Monday (newly added in PHP 4.1.0) - 42 (the 42nd week of the year)


Month

1
F ——month ——January or March January to December
2
m ——The month represented by the number ——01 to 12
3
M - three-letter abbreviation for the month - Jan to Dec
4
n ——The month represented by the number ——1 to 12
5
t —– Number of days in the month — 28 to 31


Year

1
L - Leap year, expressed as a Boolean value - 1 if it is a leap year, otherwise 0
2
o ——Year number in ISO-8601 format. Similar to Y, unless the ISO week number (W) belongs to the previous or next year, that year is used. (New in PHP 5.1.0)——1999 or 2003
3
Y —— The year expressed as a four-digit number ——1999 or 2003
4
y - two-digit year - 99 or 03


Time

1
a —— morning and afternoon ——am or pm
2
A —— Morning and Afternoon ——AM or PM
3
B ——Swatch Internet time ——000 to 999
4
g - hour, 12 hour format - no leading zeros 1 to 12
5
G - hour, 24 hour format - no leading zeros 0 to 23
6
h - hour, 12 hour format - with leading zeros 01 to 12
7
H - hour, 24 hour format - with leading zeros 00 to 23
8
i —— minutes —— 00 to 59
9
s —— seconds —— 00 to 59


Timezone

1
e - Time zone identifier (new in PHP 5.1.0) - UTC, GMT, Atlantic/Azores
2
I —— Whether it is daylight saving time —— Daylight saving time is 1, otherwise it is 0
3
T — Time zone abbreviation — for example: EST, MDT
4
Z —— Time zone difference from the current time zone, in seconds —— -43200 to 43200


Full Date/Time

1
c ——Date in ISO 8601 format (new in PHP 5) ——2004-02-12T15:19:21+00:00
2
r — Date in RFC 822 format — Thu, 21 Dec 2000 16:01:07 +0200
3
U——General description from 1970 1.1 to a certain moment, that is, Unix timestamp, see time()


For the English documentation of PHP date function date formatting characters, please refer to http://www.php.net/manual/en/function.date.php

Tips for using the date function: When using the PHP date function date to output a formatted date format, you can first write out the date format you need to output, and then use the formatting characters in the date function to combine it. It will be very easy to use. Handy.

Use PHP date function date to format Unix timestamp

The second optional parameter $timestamp of the PHP date function exists in the form of a Unix timestamp. Through this parameter, the Unix timestamp can be converted into the corresponding date format. Using Unix timestamp has many benefits in parameter passing, date calculation, etc. It is convenient and concise.

Commonly used functions in PHP to convert dates into Unix timestamps include mktime, time, and strtotime.

The PHP date function mktime is mainly used to convert date and time into Unix timestamp format.

The prototype is as follows
1
int mktime ([int $hour = date("H")
2
[,int $minute = date("i")
3
[,int $second = date("s")
4
[,int $month = date("n")
5
[,int $day = date("j")
6
[,int $year = date("Y")
7
[,int $is_dst = -1
8
]]]]]]])
Note: All parameters of the mktime function are optional, where $is_dst indicates whether it is daylight saving time. When the parameters of the mktime function are empty, it will default to the current time, similar to the time function.

The PHP date function time is mainly used to obtain the current time, which exists in Unix timestamp format.

The PHP date function strtotime is mainly used to convert the date and time described in English into a Unix timestamp.

The prototype is as follows
1
int strtotime(string $time[,int $now])


Note: The $time parameter mainly exists in the form of English text description.
The $now optional parameter is mainly expressed as a basis for $time to calculate date and time, and the default is the current Unix timestamp.

The PHP date function is mainly used to convert and output various date formats. If you want to obtain various parts of the date and time, you can obtain it by passing the Unix timestamp parameter to the getdate function. The getdate function will return a related array with the array key values ​​as follows:

01
seconds —- Number of seconds
02
minutes —- minutes
03
hours —- hours
04
mday —- Date in the month
05
wday —- Day of the week, 0 (meaning Sunday) to 6 (meaning Saturday)
06
mon —- month
07
year —- The complete year represented by four digits
08
yday —- the day of the year
09
weekday —- Text representation of the week, Sunday to Saturday
10
month —- Month text representation, January to December
11
0 —- The number of seconds since the Unix epoch, similar to the return value of time().


Through the above PHP Unix timestamp functions, combined with the PHP date function, various date format conversion, calculation and output can be performed.

PHP date calculation example:

Calculate age

01
02
$day = 1;
03
$month = 1;
04
$year = 1989;
05
 
06
$birthday = mktime(0,0,0,$month,$day,$year);
07
 
08
$nowunix = time();
09
 
10
$age = $nowunix - $birthday;
11
 
12
$age = floor($age / (365*24*60*60));
13
 
14
echo $age;
15
?>


Date addition and subtraction

01
02
$nowUnix = time();
03
 
04
$addTime = $nowUnix + (24*60*60); //Add one day to the date
05
 
06
$redTime = $nowUnix - (24*60*60);//Date minus one day
07
 
08
echo date("Y-m-j",$addTime);
09
echo date("Y-m-j",$redTime);
10
?>


Example of strtotime date calculation and format conversion

Date addition and subtraction can also be completed through the strtotime function



01
02
$nowTime = strtotime("now");
03
    echo date("Y-m-j",$nowTime)."
";
04
    
05
    $nowTime = strtotime("10 September 2010");
06
    echo date("Y-m-j",$nowTime)."
";
07
    
08
    $nowTime = strtotime("+1 day");
09
    echo date("Y-m-j",$nowTime)."
";
10
    
11
    $nowTime = strtotime("+1 week");
12
    echo date("Y-m-j",$nowTime)."
";
13
    
14
    $nowTime = strtotime("+1 week 2 days 4 hours 2 seconds");
15
    echo date("Y-m-j",$nowTime)."
";
16
    
17
    $nowTime = strtotime("next Thursday");
18
    echo date("Y-m-j",$nowTime)."
";
19
    
20
    $nowTime = strtotime("last Monday");
21
    echo date("Y-m-j",$nowTime)."
";
22
?>
至此，PHP日期函数date格式化字符含义以及部分PHP Unix时间戳函数的介绍以及相互间的转换和格式化输出实例就介绍完了，这对掌握PHP日期、时间函数的计算、与转换是非常必要的。希望对PHP入门学习的朋友有所帮助。
 
 

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