Fill up emtpy array spots with prev value - php

Question

I am using PHP 7.3.5.
I have an array with emtpy spots, which I would like to fill up values from the previous spot:
For example:
0 => 'FriAug 1',
1 => '',
2 => '',
3 => '',
4 => '',
Should result in:
0 => '01.08.2019',
1 => '01.08.2019',
2 => '01.08.2019',
3 => '01.08.2019',
4 => '01.08.2019',
I tried the following:
<?php
$arr = array (
0 => 'FriAug 1',
1 => '',
2 => '',
3 => '',
4 => '',
5 => '',
6 => '',
7 => '',
8 => '',
9 => '',
10 => '',
11 => '',
12 => '',
13 => '',
14 => '',
15 => '',
16 => '',
17 => '',
18 => '',
19 => 'SatNov 2',
20 => 'SunNov 3',
21 => '',
22 => '',
23 => '',
24 => '',
25 => '',
26 => 'MonJan 4',
27 => '',
28 => '',
29 => '',
30 => '',
31 => '',
32 => '',
33 => '',
34 => '',
35 => '',
36 => '',
37 => '',
38 => '',
39 => '',
40 => '',
41 => '',
42 => '',
43 => '',
44 => '',
45 => 'TueDec 5',
46 => '',
47 => '',
48 => '',
49 => '',
50 => '',
51 => '',
52 => '',
53 => '',
54 => '',
55 => '',
56 => '',
57 => '',
58 => '',
59 => '',
60 => '',
61 => '',
62 => 'WedNov 6'
);
$resArr = array();
foreach ($arr as $key => $v) {
$prev = $key - 1;
if($arr[$key] === '') {
array_push($resArr, strtotime(preg_replace("^.{0,3}","", $arr[$prev])));
} else {
array_push($resArr, strtotime(preg_replace("^.{0,3}","", $arr[$key])));
}
}
print_r($resArr);
My final result should look like the following:
// Wanted Result:
0 => '01.08.2019',
1 => '01.08.2019',
2 => '01.08.2019',
3 => '01.08.2019',
4 => '01.08.2019',
5 => '01.08.2019',
6 => '01.08.2019',
7 => '01.08.2019',
8 => '01.08.2019',
9 => '01.08.2019',
10 => '01.08.2019',
11 => '01.08.2019',
12 => '01.08.2019',
13 => '01.08.2019',
14 => '01.08.2019',
15 => '01.08.2019',
16 => '01.08.2019',
17 => '01.08.2019',
18 => '01.08.2019',
19 => '02.11.2019',
20 => '03.11.2019',
21 => '03.11.2019',
22 => '03.11.2019',
23 => '03.11.2019',
24 => '03.11.2019',
25 => '03.11.2019',
26 => '04.11.2019',
27 => '04.11.2019',
28 => '04.11.2019',
29 => '04.11.2019',
30 => '04.11.2019',
31 => '04.11.2019',
32 => '04.11.2019',
33 => '04.11.2019',
34 => '04.11.2019',
35 => '04.11.2019',
36 => '04.11.2019',
37 => '04.11.2019',
38 => '04.11.2019',
39 => '04.11.2019',
40 => '04.11.2019',
41 => '04.11.2019',
42 => '04.11.2019',
43 => '04.11.2019',
44 => '04.11.2019',
45 => '05.12.2019',
46 => '05.12.2019',
47 => '05.12.2019',
48 => '05.12.2019',
49 => '05.12.2019',
50 => '05.12.2019',
51 => '05.12.2019',
52 => '05.12.2019',
53 => '05.12.2019',
54 => '05.12.2019',
55 => '05.12.2019',
56 => '05.12.2019',
57 => '05.12.2019',
58 => '05.12.2019',
59 => '05.12.2019',
60 => '05.12.2019',
61 => '05.12.2019',
62 => '06.11.2019'
);
However, I only get null/false values in my final output.
Any suggestions what I am doing wrong?
I appreciate your replies!

Answer 1

One of the problems is the use of the regex - your pattern isn't correct - but as it's just removing 3 chars of the front, it's easier to use substr() to remove them.
The second part is that you just look at the previous array position in the source array - which may also be blank. This version just stores the last value generated (in $prev) and keeps on using it when needed...
$resArr = array();
$prev = "";
foreach ($arr as $key => $v) {
if($arr[$key] === '') {
array_push($resArr, $prev);
} else {
$prev = date("d.m.Y",strtotime(substr($arr[$key], 3)));
array_push($resArr, $prev);
}
}
This could be simplified without losing too much clarity to...
$resArr = array();
$prev = "";
foreach ($arr as $key => $v) {
if($arr[$key] !== '') {
$prev = date("d.m.Y",strtotime(substr($arr[$key], 3)));
}
array_push($resArr, $prev);
}