Detailed explanation of php timestamp (UNIX) usage

Timestamp is the number of seconds since January 1, 1970 (00:00:00 GMT). It is also called Unix Timestamp.

Unix timestamp, also known as Unix time (Unix time), POSIX time (POSIX time), is a time representation method, defined as January 1, 1970 Greenwich Time The total number of seconds since 00:00:00 to now. Unix timestamps are not only used in Unix systems and Unix-like systems, but are also widely used in many other operating systems. This article mainly introduces the usage of php UNIXtimestamp, and analyzes the related functions and usage techniques of php Unix timestamp in the form of examples, as follows:

Time stamps are the creation, modification, and access times in the file attributes . The digital timestamp service is one of the security services of the Web website, which can provide security protection for the date and time information of electronic files.

The advantage of timestamp is:

The encrypted value can be changed to prevent the value from being stolen and illegally reused, and plays the role of encryption. . Timestamps mainly rely on time and generate a unique value within an agreed period of time.

UNIX timestamp

In the UNIX system, the date and time are expressed as the time from 0:00 on January 1, 1970 to the current moment Number of seconds. This time is called a UNIX timestamp and is represented as a 32-bit binary number. This time representation method is supported in different operating systems. The same time is represented by the same UNIX timestamp in UNIX and Windows, so there is no need to convert in different systems.

The current UNIX timestamp is represented by a 32-bit binary number, and the 32-bit binary value range is (-2147483648~+2147483647). Since the system does not support negative timestamps, the current UNIX timestamp can represent The maximum time is 3:14:7 on January 19, 2038, and the timestamp of this moment is 2147483647. After this time, the number of binary digits of the UNIX timestamp needs to be extended.

PHP Gets the timestamp of a specified date

Apply the mktime() function in PHP to convert a time into UNIX timestamp value.

The syntax is as follows

mktime(hour,minute,second,month,day,year,is_dst)

Parameter	Description
hour	Optional. Specified hours.
minute	Optional. Specified minutes.
second	Optional. Specifies seconds.
month	Optional. Specifies the numeric month.
day	Optional. Specify days.
year	可选。规定年。在某些系统上，合法值介于 1901 - 2038 之间。不过在 PHP 5 中已经不存在这个限制了。
is_dst	可选。如果时间在日光节约时间(DST)期间，则设置为1，否则设置为0，若未知，则设置为-1。 自 5.1.0 起，is_dst 参数被废弃。因此应该使用新的时区处理特性。

例如：

echo "时间戳：".mktime().&#39;<br>&#39;;//返回当前时间戳
echo "任意日期：".date("Y-m-d",mktime(0,0,0,2,21,1996)).&#39;<br>&#39;;
echo "当前日期: ".date("Y-m-d",mktime()).&#39;<br>&#39;;

运行结果为：

时间戳：1458979695
任意日期：1996-02-21
当前日期: 2016-03-26

获取当前时间戳

PHP通过time()函数获取当前的UNIX时间戳。

语法如下：

int time(void);

该函数没有参数，返回值为UNIX时间戳的整数值。

例如：

echo time()."<br>";//输出当前时间戳
$nextWeek = time()+(7*24*60*60);//一个星期七天，一天24小时，一个小时60分，一分60秒
echo "Now: ".date("Y-m-d")."<br>";
echo "Next Week: ".date("Y-m-d",$nextWeek);

运行结果为

1458980073
Now: 2016-03-26
Next Week: 2016-04-02

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