How to list values of an array in order using the sort function in PHP

Question

I have an array. Examples of the string values inside the array are

I need to list these in date order. I couldn't sort them based on how they were named because 28-12-2018 would be seen as greater than 10-01-2019 for example (as 28 is larger than 10) when in fact it's not, as the first value is for December the previous year.

Therefore I made tweaks to display the values as as YYYYMMDD

However I cannot get the values to order properly when looping through them

//this is my array
$row['file_name'];

//remove hyphens from file name and display only 8 characters
$date = substr(str_replace("-", "", $row['sitma_file_name']), 0, 8);

//get the year part of $date
$year = substr($date,4);

//get the month part of $date
$month = substr($date,2, 2);

//get the day part of $date
$day = substr($date, 0, 2);

//concatenate above variables to make $date display as YYYYMMDD
$date = $year . $month . $day;

//put $date in an array
$date_array = array($date);

//sort the array
sort($date_array);

//loop through array and echo values 
foreach ($date_array as $value){
    echo $value;
}

Expected results are

However the actual results are

sort the array as given https://stackoverflow.com/a/40462935/9223416 and then do the functionalities you are doing for removing hyphens — Sanjit Bhardwaj, Jan 31 '19 at 11:28
@ginomay This can't be your actual code. What you are creating is an array with one value only. Please post the code you are really using — yunzen, Jan 31 '19 at 11:30
@yunzen The code I have posted is the actual code I am using. My array is $row['file_name'] which contains 5 values. I remove the hyphens and display only 8 characters using str_replace() and substr() and then put all this inside a new variable $date. — ginomay89, Jan 31 '19 at 11:37
This can't be. I get a warning: `substr() expects parameter 1 to be string, array given` — yunzen, Jan 31 '19 at 11:47

score -1 · Answer 1 · answered Jan 31 '19 at 11:33

-1

Here is solution:

$dates = [
    '10-01-2019',
'28-12-2018',
'16-01-2019',
'21-01-2019',
'14-11-2018'
    ];

usort($dates, function($a, $b){
    $dt1 = explode('-',$a);
    $dt2 = explode('-', $b);

    return ($dt2[2].$dt2[1].$dt2[0]) < ($dt1[2].$dt1[1].$dt1[0]);
});

echo '<pre>';
print_r($dates);

Output:

Array
(
    [0] => 14-11-2018
    [1] => 28-12-2018
    [2] => 10-01-2019
    [3] => 16-01-2019
    [4] => 21-01-2019
)

answered Jan 31 '19 at 11:33

mukund

2,253
1
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*"here is solution"*. Great explanation. – Andreas Jan 31 '19 at 12:25

How to list values of an array in order using the sort function in PHP

1 Answers1