How to Convert a Date to a Timestamp in PHP

  1. Using Strtotime() Function to Convert a Date to a Timestamp in PHP
  2. Using Strptime() Function to Convert a Date to a Timestamp in PHP
  3. Using getTimestamp() Function to Convert a Date to a Timestamp in PHP
  4. Using Format() Function to Convert a Date to a Timestamp in PHP

In this article, we will introduce methods to convert a date to a timestamp in PHP.

  • Using strtotime() function
  • Using strptime() function
  • Using getTimestamp() function
  • Using format() function

Using Strtotime() Function to Convert a Date to a Timestamp in PHP

The built-in function strtotime() converts a date to a Unix timestamp. A Unix timestamp is the total number of seconds calculated from the Unix epoch(January 1st, 1970). The correct syntax to use this function is as follows

strtotime($dateString,$timeNow);

This function has two parameters. $dateString is the date/time string that should comply with PHP valid format. It is a mandatory parameter. The other parameter $timeNow is optional, it is the timestamp that is used for calculating relative dates. The current time now is the default value if the second parameter is omitted.

<?php
$timestamp = strtotime("23-04-2020");
echo "The timestamp is $timestamp.";
?>

The date here is in the format "d-m-Y". We have only passed a single parameter as it will convert the date to a Unix timestamp.

Output:

The timestamp is 1587600000.

Using Strptime() Function to Convert a Date to a Timestamp in PHP

This is another function to convert a date to a Unix timestamp. It does not convert the date directly to a timestamp. It returns an array that tells about the seconds, minutes, hours, and several other details. We can use these details to convert a date to a timestamp.

strptime($dateString, $format);

It has two mandatory parameters. $dateString is the date string and $format is the format to parse $dateString.

<?php
$array = strptime('23-04-2020', '%d-%m-%Y');
$timestamp = mktime(0, 0, 0, $array['tm_mon']+1, $array['tm_mday'], $array['tm_year']+1900);
echo "The timestamp is $timestamp.";
?>

Output:

The timestamp is 1587600000.

After generating the array, mktime() function converts the date to a timestamp.

The syntax of mktime() function is

mktime(hour, minute, second, month, day, year, is_dst)

is_dst specifies whether the date-time is a daylight saving time, but is removed from PHP 7.0.0.

Warning

We shall add 1 to $array['tm_mon'] and then use the sum as parameter of month in mktime, because $array['tm_mon'] starts from 0, or in other words, $array['tm_mon'] of January is 0.

Using getTimestamp() Function to Convert a Date to a Timestamp in PHP

getTimestamp() method of DateTime object is a simple method to convert a date to a timestamp. It has another way of representation date_timestamp_get() that is the procedural style representation.

$datetimeObject->getTimestamp(); 

We will create a Datetime object to call this function. This is the object-oriented style of calling a function.

<?php
$date = new DateTime('2020-04-23');
$timestamp = $date->getTimestamp();
echo "The timestamp is $timestamp.";
?>

The object $date of Datetime class has called the method getTimestamp() to convert the date to a Unix timestamp.

Output:

The timestamp is 1587600000.

Using Format() Function to Convert a Date to a Timestamp in PHP

We can also use the format() method of DateTime to convert a date to a timestamp. This method has another representation date_format() that is the procedural style representation of the format() function.

$datetimeObject->format("U"); 

To convert a date to a timestamp, the format that we will pass as a string is "U".

<?php
$dateObject = new DateTime('2020-04-23');
$timestamp = $dateObject->format("U");
echo "The timestamp is $timestamp.";
?>

The object $dateObject of the Datetime class has called the function format() to convert the date to a Unix timestamp.

Output:

The timestamp is 1587600000.

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