How can I find the maximum and minimum date in an array?

Question

I need to find the maximum and minimum date from a given array using PHP.

I have $date_arr which contains following values,

  $date_arr = array('0'=>'20-05-2015','1'=>'02-01-2015','2'=>'30-03-2015');

Here, I need to get the larger date as '20-05-2015' and the minimum date as '02-01-2015'.

How can I achieve this?

Answer 1

<?php

$date_arr=array(0=>'20-05-2015',1=>'02-01-2015',2=>'30-03-2015');

usort($date_arr, function($a, $b) {
    $dateTimestamp1 = strtotime($a);
    $dateTimestamp2 = strtotime($b);

    return $dateTimestamp1 < $dateTimestamp2 ? -1: 1;
});

echo 'Min: ' . $date_arr[0];
echo '<br/>';
echo 'Max: ' . $date_arr[count($date_arr) - 1];


?>

Answer 2

max() and min() works fine with your array:

echo "Latest Date: ". max($dates)."\n";
echo "Earliest Date: ". min($dates)."\n";

Answer 3

please Try this

$date_arr = array('0' => '20-05-2015', '1' => '02-01-2015', '2' => '30-03-2015');
for ($i = 0; $i < count($date_arr); $i++)
{
    if ($i == 0)
    {
        $max_date = date('Y-m-d H:i:s', strtotime($date_arr[$i]));
        $min_date = date('Y-m-d H:i:s', strtotime($date_arr[$i]));
    }
    else if ($i != 0)
    {
        $new_date = date('Y-m-d H:i:s', strtotime($date_arr[$i]));
        if ($new_date > $max_date)
        {
            $max_date = $new_date;
        }
        else if ($new_date < $min_date)
        {
            $min_date = $new_date;
        }
    }
}
echo date('d-m-Y',strtotime($max_date));
echo date('d-m-Y',strtotime($min_date));

Answer 4

Thought it doesn't technically offer the lowest computational time complexity, array_multisort() is a sensible, readable, concise approach. My snippet only calls strtotime() on each element once -- usort() cannot match this claim.

Code: ( Demo )

$dates = ['20-05-2015', '02-01-2015', '30-03-2015', '10-01-1990'];
array_multisort(array_map('strtotime', $dates), $dates);

printf(
    "Latest Date: %s\nEarliest Date: %s",
    $dates[array_key_last($dates)],
    $dates[0]
);

Output:

Latest Date: 10-01-1990
Earliest Date: 20-05-2015

---

To arrive at the same result by calling min() and max() , just create a formatted copy of the dates in unix time.

Code: ( Demo )

$unix = array_map('strtotime', $dates);

printf(
    "Latest Date: %s\nEarliest Date: %s",
    date('d-m-Y', max($unix)),
    date('d-m-Y', min($unix))
);

---

If you want to use usort() , here is the most modern syntax with the spaceship operator and arrow function syntax. ( Demo )

usort($dates, fn($a, $b) => strtotime($a) <=> strtotime($b));

printf(
    "Latest Date: %s\nEarliest Date: %s",
    $dates[array_key_last($dates)],
    $dates[0]
);

---

This task can surely be accomplished tens of different ways. I considered writing a foreach() loop with conditions to maintain temporary variables while making iterated comparisons, but I felt it was prohibitively convoluted for a rather simple task.

Answer 5

$date_arr=array(0=>'2015-05-20',1=>'2015-02-21',2=>'2015-04-13',3=>'2020-04-30',4=>'2020-04-13');

$max_date=$date_arr[0];
for($i=0;$i<count($date_arr);$i++)
{
    echo $date_arr[$i]. ' ,';
    if( $max_date < $date_arr[$i+1])
    {
        $max_date=$date_arr[$i+1];
    }
}  
echo " Max= ". $max_date;