PHP time and date, PHP time and date
PHP provides a large number of built-in functions, allowing developers to easily process time, greatly improving work efficiency. This section describes some common PHP date and time functions as well as date and time processing.
Common date and time processing functions
Letter count |
Description |
Checkdate |
Verify the time function to determine whether the time is valid. If the time is valid, true is returned; otherwise, false is returned. |
Date_default_timezone_get |
Obtains the default time zone used by the date and time functions of the script. |
Date_default_timezone_set |
Set the default time zone of the datetime Function |
Date |
Format a local time/date |
Getdate |
Get date/time information |
Gettimeofday |
Get current time |
Localtime |
Get local time |
Microtime |
Returns the current Timestamp and the number of microseconds. |
Mktime |
Obtain a UNIX Timestamp |
Strtotime |
Parses the date and time description of any English text into a UNIX Timestamp |
Time |
Returns the current UNIX timestamp. |
System Time Zone settings
During the learning process, we found that the time obtained through the date () function is different from the local time. This is because PHP5 has rewritten the date () function. Therefore, the current date and time functions are eight hours less than the system time. In PHP, the standard Greenwich Mean Time (Zero Time Zone) is set by default ). There are two ways to change the time zone settings in PHP:
1. Modify the settings in the php. ini file, find the; date. timezone = option under [date], change this option to date. timezone = Asia/Hong_Kong, and restart the apache server.
2. In the application, add the following functions before using the time and date functions:
Date_default_timezone_set("Asia/Hong_Kong"); after the setting is complete, the date () function can be used normally without any time difference.
UNIX Timestamp
The timestamp is the time when file attributes are created, modified, and accessed. Digital time stamp service (DTS) is one of the security services for web websites. It can protect the date and time of electronic files.
The timestamp is an encrypted credential document. It consists of three parts:
2. The files whose timestamps need to be added are encrypted using Hash codes to form a summary.
2. Date and time information of the file accepted by DTS.
2. Encrypt accepted DTS files.
The digital time is added by the authentication unit DTS, which is based on the time when DTS receives the file. The principle of timestamp is to convert the value of time to the encrypted value through other encryption methods. After the time changes, the encrypted value also changes. The advantage of the timestamp is that the changed encryption value can prevent unauthorized reuse of the value after it is stolen, which plays a role in encryption. The timestamp mainly depends on time and generates a unique value within the specified period of time.
Mktime () function
Syntax:
Int mktime (int hour, int minute, int month, int day, int year, int [is_dst])
Parameter |
Description |
Hour |
Hours |
Minute |
Minutes |
Second |
Seconds (within one minute) |
Month |
Number of months |
Day |
Days |
Year |
Number of copies per year |
Is_dst |
The is_dst parameter can be set to 1 during the period. If not, it is set to 0. If you are not sure whether it is a period, it is set to-1 (default) |
Note: The valid timestamp typically ranges from 20:45:54 to GMT ~ January 19, 2038 03:13:07 (this range conforms to the minimum and maximum values of 32-bit signed integers ). In Windows, the range is from January 1, January 1, 1970 ~ May January 19, 2038.
Date () function
Date (string format, int timestamp)
This function returns the string generated by the timestamp parameter in the specified format. The timestamp parameter is optional. If it is omitted, the current time is used. The format parameter allows developers to output time and date in the specified format.
Date_default_timezone_set (PRC); // Set Beijing time.
format Character |
Description |
Return Value example |
Day |
--- |
--- |
D |
The day of the month, which has two digits leading to zero |
01To31 |
D |
The day of the week. The text indicates three letters. |
MonToSun |
J |
The day of the month, with no leading zero |
1To31 |
L(Lowercase letters of "L) |
Day of week, complete text format |
SundayToSaturday |
N |
The day of the week represented by a number in the ISO-8601 format (New in PHP 5.1.0) |
1(Monday)7(Sunday) |
S |
English suffix after the number of days per month, 2 Characters |
St,Nd,RdOrTh. AndJUse together |
W |
The day of the week, represented by a number |
0(Sunday)6(Saturday) |
Z |
The day of the year. |
0To365 |
Week |
--- |
--- |
W |
The week of the year in ISO-8601 format, starting from Monday each week (New in PHP 4.1.0) |
For example:42(The first week of the year) |
Month |
--- |
--- |
F |
The month in the complete text format, such as January or March. |
JanuaryToDecember |
M |
Number indicates the month, with a leading zero |
01To12 |
M |
The month abbreviated to three characters. |
JanToDec |
N |
Number indicates the month, with no leading zero |
1To12 |
T |
Number of days in a given month |
28To31 |
Year |
--- |
--- |
L |
Is it a leap year? |
If the leap year is1Otherwise0 |
O |
The number of years in ISO-8601 format. This andYExcept for the week number of ISO (W) Belongs to the previous year or the next year, that year is used. (New PHP 5.1.0) |
Examples:1999Or2003 |
Y |
The year in which the four digits represent the complete number. |
For example:1999Or2003 |
Y |
A two-digit year |
For example:99Or03 |
Time |
--- |
--- |
A |
Morning and afternoon values in lower case |
AmOrPm |
A |
Upper-case morning and afternoon values |
AMOrPM |
B |
Swatch Internet standard |
000To999 |
G |
Hour, 12-hour format, no leading zero |
1To12 |
G |
Hour, in 24-hour format, no leading zero |
0To23 |
H |
Hour, 12-hour format, with leading zero |
01To12 |
H |
Hour, in 24-hour format, with a leading zero |
00To23 |
I |
Minutes with a leading zero |
00To59> |
S |
Number of seconds, with a leading zero |
00To59> |
U |
Millisecond (New in PHP 5.2.2 ). Note thatDate ()Function always returns000000It only accepts integer Parameters, while DateTime: format () supports milliseconds. |
Example:654321 |
Time Zone |
--- |
--- |
E |
Time zone ID (New in PHP 5.1.0) |
For example:UTC,GMT,Atlanta/Azores |
I |
When it is enabled or not |
If it is enabled1Otherwise0 |
O |
Hours different from Greenwich Mean Time |
For example:+ 0200 |
P |
Difference from Greenwich Mean Time (GMT), separated by colons between hours and minutes (New in PHP 5.1.3) |
For example:+ 0: 00 |
T |
Time zone of the Local Machine |
For example:EST,MDT([Note] the full text format is in Windows, for example, "Eastern Standard Time". The Chinese version displays "Chinese Standard Time "). |
Z |
The number of seconds of the time difference offset. The Time Zone offset to the west of UTC is always negative, and the time zone offset to the east of UTC is always positive. |
-43200To43200 |
Complete date/time |
--- |
--- |
C |
Date in ISO 8601 format (New in PHP 5) |
2004-02-12T15: 19: 21 + 00: 00 |
R |
Date in RFC 822 format |
For example:Thu, 21 Dec 2000 16:01:07 + 0200 |
U |
Number of seconds since Unix epoch (January 1 1970 00:00:00 GMT) |
See time () |
Getdate () function
This function returns date and time information in array format. If there is no timestamp, the current time prevails.
Yuansu |
Description |
Seconds |
Seconds, return value 0 ~ 59 |
Minutes |
Minutes. The returned value is 0 ~ 59 |
Hours |
Hour, return value is 0 ~ 23 |
Mday |
The day of the month. The returned value is 1 ~ 31 |
Wday |
The day of the week. The returned value is 0 (Sunday )~ 6 (Saturday) |
Mon |
Number of months. The returned value is 1 ~ 12 |
Year |
The full year represented by four digits. the return value is 2000 or 2008. |
Yday |
The day of the year, the return value is 0 ~ 365 |
Weekday |
Indicates the complete text of the day of the week. The returned value is Sunday ~ Saturday |
Month |
The complete text of the month. The returned value is January ~ December |
0 |
Returns the number of seconds from the UNIX epoch. |
Compare the two time ranges
In actual development, we often encounter two time sizes. The time in PHP cannot be compared directly. Therefore, the time must be output as the timestamp format before comparison. This is a common method.
Two functions can implement this function. Here we use the strtotime () function, which can resolve the datetime description of any English text to a UNIX timestamp. The syntax of this function is:
Int strtotime (string time, int now)
This function has two parameters. If the time format of the parameter is absolute time, the now parameter does not work. If the time format of the parameter is relative time, the corresponding time is provided by the parameter now, if the now parameter is not provided, the corresponding time is the current time. If the parsing fails,-1 is returned.
Calculate the running time of the page script
Search engines are often used when Browsing websites. When searching for information, careful users will find that at the bottom of the search results, there are generally "the search time is ...... Second. The microtime () function is used here, which returns the current UNIX Timestamp and the number of microseconds. The string in the format of msec sec, where sec is the current UNIX Timestamp and msec is the microseconds. The function format is:
String microtime (void)
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