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PHP, as a commonly used server-side scripting language, often involves time-related operations, such as calculating time intervals, time format conversion, etc. Timestamp is one of the very important time representation methods in PHP. This article will delve into how PHP obtains timestamp.
1. What is a timestamp?
Timestamp (Timestamp) is a way of expressing time. It is an integer that represents the beginning of January 1, 1970. The number of seconds from 0:00:00 (Greenwich Mean Time) to the current time, also known as a Unix timestamp. Timestamps are widely used in the computer field, especially in web development.
In PHP, we can use the time() function to get the current timestamp, for example:
echo time(); // 输出当前时间戳，例如：1565949030
2. How to get the timestamp of the specified time
In addition to getting the timestamp of the current time, we also need to get the timestamps of some specified times, such as a specific time, a certain date, etc. PHP provides several ways to obtain the timestamp of a specified time:
mktime() function can return a timestamp of a specified date. Its parameters can contain hour, minute, second, month, day, year and other information. For example:
echo mktime(12, 30, 0, 8, 15, 2019); // 输出：1565857800
This means that the timestamp at 12:30 on August 15, 2019 is 1565857800.
The strtotime() function can convert the date and time description of any English text into a timestamp. For example:
echo strtotime('2019-08-15 12:30:00'); // 输出：1565857800
This is similar to the mktime() function, except that the format of the parameters passed in is different.
PHP also provides the DateTime class, which can conveniently handle dates and times. Using the DateTime class, we can first create a DateTime object, then obtain the time in the specified format through the object's format() method, and then obtain the timestamp through the object's getTimestamp() method. For example:
$dateTime = new DateTime('2019-08-15 12:30:00');
echo $dateTime->format('Y-m-d H:i:s'); // 输出：2019-08-15 12:30:00
echo $dateTime->getTimestamp(); // 输出：1565857800
3. How to format the timestamp
Time stamps usually do not conform to human-readable format, so we need to format the timestamp when displaying the time Convert to a readable date/time string. There is a date() function in PHP that can be used to format time.
The first parameter of the date() function is a format string, which can contain various identifiers to represent different time parts. For example, common identifiers are:
For example, format the timestamp in the form of year-month-day:
echo date('Y-m-d', time()); // 输出：2019-08-16
The second parameter is optional. If not passed in, the current timestamp will be used by default. .
4. How to add or subtract specified time intervals from timestamps
In actual development, it is often necessary to add or subtract some time intervals from specified timestamps. For example, one hour, one day, one month, etc. You can use the strtotime() function in PHP to achieve this function.
The first parameter of the strtotime() function is the timestamp, and the second parameter is the time interval, which can be any string representing time. For example, add one hour to the current timestamp and output a readable date and time:
$timestamp = time() + 3600; // 在当前时间戳中加上一小时的时间间隔
echo date('Y-m-d H:i:s', $timestamp); // 输出增加一小时后的日期时间
You can also use relative time format, for example:
$timestamp = strtotime('+1 day', time()); // 在当前时间戳中加上一天的时间间隔
echo date('Y-m-d H:i:s', $timestamp); // 输出增加一天后的日期时间
strtotime() function can also be used Used to calculate time intervals, such as calculating the difference in days between two timestamps:
$timestamp1 = strtotime('2019-08-15');
$timestamp2 = strtotime('2019-08-20');
$days = ($timestamp2 - $timestamp1) / (60 * 60 * 24);
echo $days; // 输出5
5. Summary
In this article, we discussed how to obtain Timestamps, how to get a timestamp at a specified time, how to format a timestamp, and how to add or subtract time intervals from a timestamp. Timestamps are a very commonly used time representation method in web development. Mastering relevant knowledge can greatly improve our development efficiency.
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