How to convert date to timestamp using PHP

Timestamps are a very common concept when developing with PHP. However, sometimes you need to convert a date to a timestamp for processing. In this article, we will learn how to convert date to timestamp using PHP.

1. Use strtotime() function to convert date to timestamp

strtotime() function is a very useful function in PHP, it can Convert a date string to a timestamp. Let's look at a simple example. Suppose we want to convert "2021-08-12" to a timestamp. The code is as follows:

$date = "2021-08-12";
$timestamp = strtotime($date);
echo $timestamp;

The above code will output:

1628736000

The timestamp represents 0 o'clock on August 12, 2021.

2. Convert date to timestamp using date object

There is a DateTime class in PHP that can be used to handle dates and times. We can convert a date into a timestamp by instantiating a DateTime object. This method is more flexible than using strtotime() and allows greater control over date format and time zone.

The following is an example of converting "2021/08/12" into a timestamp:

$dateString = '2021/08/12';
$date = new DateTime($dateString);
echo $date->getTimestamp();

The output of the above code is:

1628716800

It represents the year 2021 12 o'clock in the morning on August 12th.

3. Date format string

In the above two examples, we used "2021-08-12" and " 2021/08/12" as a date string. Different date formats may require different processing methods. Some common date formats are as follows:

• Y-m-d: year-month-day
• Y/m/d: year/month /Day
• Y-m-d H:i:s：Year-month-day hour:minute:second
• Y/m/d H:i:s：Year/month/day hour:minute :Seconds

If you need to use a different date format, just modify the corresponding date format string.

4. Dealing with time zones

Finally, we need to pay attention to time zones. If your server and client are in different time zones, the timestamp value will be different accordingly. We should always use a consistent time zone when dealing with dates.

When setting a DateTime object, you can use the setTimezone() method to set the time zone. For example, convert "2021/08/12" to a timestamp in New York time (America/New_York):

$dateString = '2021/08/12';
$date = new DateTime($dateString, new DateTimeZone('America/New_York'));
echo $date->getTimestamp();

The above code will output:

1628784000

This is the date in the New York time zone timestamp.

Summary

In PHP, converting dates to timestamps is a very common need. We can do this using the strtotime() function or the DateTime class. At the same time, we also need to pay attention to using a unified date format and time zone to ensure that the timestamp value is always correct.

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