What is the purpose of the strtotime function in PHP?

The `strtotime()` function is a built-in function in PHP that is used to convert human-readable date and time strings into UNIX timestamps. UNIX timestamps represent the number of seconds that have elapsed since January 1, 1970.

The purpose of the `strtotime()` function is to return a UNIX timestamp corresponding to a given date and time string. This function is very useful and can be used for various date and time operations such as comparing dates, calculating differences between dates, and formatting dates.

Here is an example of using the `strtotime()` function:

$date = "2022-12-31";
$timestamp = strtotime($date);
echo $timestamp; // 输出：1672444800

In the example above, the `strtotime()` function converts the string `”2022-12-31″` to the corresponding UNIX timestamp `1672444800`. You can use this timestamp for subsequent date and time operations.

It is important to note that the `strtotime()` function also supports many other date and time string formats, such as relative dates (such as “tomorrow”, “next week”), relative times (such as “+1 day”, “-2 weeks”), and special dates (such as “now”, “yesterday”). It can also parse date and time strings that contain timezone information.

In conclusion, the `strtotime()` function makes it more convenient and flexible to handle dates and times in PHP.