Detailed explanation of time and timestamp conversion in PHP

In PHP, conversion between timestamps and dates is a very common operation, because we need to convert timestamps into specific date formats, or convert date formats into timestamps for storage and calculation. Next we will explain in detail time and timestamp conversion in PHP.

1. Introduction to timestamp

Timestamp is also called "Unix timestamp", which refers to the "number of seconds from 00:00:00 on January 1, 1970 to a certain time" ". Unix timestamps use Greenwich Mean Time (GMT).

In PHP, to get the timestamp of the current time, you can use the time() function:

$timestamp = time();
echo $timestamp; // 输出当前时间戳

2. Convert the timestamp to date format

When converting timestamps to date format, we need to use PHP's date() function. The parameter of this function is a format string used to specify the format of the output date.

For example, to convert the timestamp into the "year-month-day" format, you can use the following code:

$timestamp = time();
$date = date('Y-m-d', $timestamp);
echo $date; // 输出“年-月-日”格式的日期

Where, Y represents the four-digit year , m represents the two-digit month, d represents the two-digit date. For more formatting characters, please consult the PHP official documentation.

3. Convert date format to timestamp

When converting date format to timestamp, we need to use PHP’s strtotime() function, which can convert Converts a datetime formatted string to a Unix timestamp.

For example, to convert the date string "2021-08-31 10:00:00" into a timestamp, you can use the following code:

$date = '2021-08-31 10:00:00';
$timestamp = strtotime($date);
echo $timestamp; // 输出时间戳

4. Consider the impact of time zone

When using timestamp and date format conversion, special attention needs to be paid to the impact of time zone. Unix timestamps use the GMT time zone, and our commonly used time zone may be UTC 8, so time zone conversion is required.

You can use PHP's date_default_timezone_set() function to set the time zone. For example, to set the time zone to East Eighth District, you can use the following code:

date_default_timezone_set('Asia/Shanghai');

5. Summary

The above is the conversion between timestamp and date formats in PHP. They are used on the Web It is widely used in development. We need to understand the definition of timestamp and the time zone it uses, and we also need to be proficient in the use of the date() and strtotime() functions. I hope this article can be helpful to PHP developers.

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