# Using PHP to find out a date, a period of time or the difference as text

In this post you will learn how to output times with PHP and also WordPress. This includes the current date; dates in the future, or in the past. Also how to find out days within a time period. Have fun!

## time()

With `time()` the current timestamp can be output. The current timestamp always consists of seconds. The starting date is always January 1, 1970 GMT. This means that `time()` always counts the seconds since January 1, 1970 GMT for us.

```php
time(); // Now as timestamp
```

Since the seconds are printed here, the time can also be printed. For this we use `date()` to display the time.

```php
date('H:i'); // Now as hour and minute
```

## date()

The best known and simplest function is the `date()` function provided by PHP. With this function you can easily output the current date.

```php
date('d.m.Y'); // Now as date
```

As a second parameter you can also specify a timestamp. For example, a timestamp from the past will be prefixed as date.

```php
date('d.m.Y', strtotime('-1 week')); // Now minus 1 week, as date
```

## strtotime()

With `strtotime()` you can convert a date or time string into seconds. We used this function above to get Today a week ago.

```php
strtotime('-1 weeks'); // Now a week ago
```

**See also:**
* [Time and date formats](https://www.php.net/manual/en/datetime.formats.php) - php.net

## DateTime()

With the `DateTime()` class PHP offers us something really useful. The class can be used to modify, format and output strings.

```php
$date = new \DateTime('now'); // Now

$date->modify('+2 days'); // Now plus two days
echo $date->format('d.m.Y'); // Return the result as date

$date->modify('+2 days'); // Now plus four days
echo $date->format('d.m.Y');
```

With `getTimestamp()` you can also return the timestamp. This is useful if you want to do comparisons.

```php
$date = new \DateTime('01.01.2021'); // 01 January 2021

if ($date->getTimestamp() < time()) {
   echo 'January 01, 2021 is in the past!';
}
```

## DatePeriod()

With `DatePeriod()` you can generate all days between two `DateTime()` objects. This is useful if you want to create a chart for example and also need the days between two dates.

```php
$start = new \DateTime('01.01.2021');
$end = new \DateTime('15.01.2021');

$interval = new \DateInterval('P1D'); // P1D indicates that the days are counted
$period = new \DatePeriod($start, $interval,$end);

foreach ($period as $date) {
    echo $date->format('d.m.Y') . '<br>';
}
```

**See also:**
* [DateInterval()](https://www.php.net/manual/en/class.dateinterval.php) - php.net

## WordPress: human_time_diff()

With `human_time_diff()` WordPress offers us another useful function. With this you can calculate the distance between two timestamps. WordPress then converts this distance into a record.

For example, 1 week ago can be printed if the date is one week ago.

```php
printf('before %s', human_time_diff(strtotime('-1 weeks')); // 1 week ago
```

**See also:**
* [human_time_diff()](https://developer.wordpress.org/reference/functions/human_time_diff/) - WordPress.org