How many digits are timestamps in php

For web developers, timestamps are a very important tool. In PHP, we can get the timestamp of the current time through the built-in time() function. A timestamp is an integer representing the number of seconds between the current time and the beginning of the Unix epoch (January 1, 1970).

So, how many digits does the PHP timestamp have? The answer is: PHP timestamps are usually 10 digits. However, there is another case where it is 13 bits (millisecond timestamp). Let’s take a look at it below.

1. 10-digit timestamp

Normally, PHP's timestamp is 10 digits, representing the number of seconds since the Unix epoch. The current timestamp can be obtained through the time() function:

echo time(); //输出当前时间戳

The timestamp obtained through this function is an integer, for example: 1624278852. This number represents the number of seconds that have elapsed since the Unix epoch to the current time (June 21, 2021 18:47:32).

Simply put, this number represents the number of seconds from the beginning of the Unix epoch to the current time.

2. 13-digit timestamp

In some high-performance computer systems, if 10-digit timestamps are used, duplicate timestamps will occur. question. At this time, we need to use a 13-digit timestamp.

Different from the 10-digit timestamp, the 13-digit timestamp represents the number of milliseconds from the beginning of the Unix epoch to the present. In PHP, we can get the 13-digit timestamp through the following method:

echo round(microtime(true) * 1000);

Note that the microtime(true) function is used here, which returns the current number of microseconds (six digits after the decimal point), and then The result is multiplied by 1000 to get the milliseconds of the current time, and finally rounded to get a 13-digit timestamp.

In some situations where high-precision timestamps are required, we can use 13-digit timestamps to ensure the uniqueness of the timestamp.

Summary

In PHP, timestamp is a very important concept, through which time can be compared and calculated. Typically, PHP timestamps are 10 digits representing the number of seconds since the Unix epoch. But in some high-precision situations, we need to use a 13-digit timestamp to represent the number of milliseconds from the beginning of the Unix epoch to the present.

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