Insert element into order position of array? - php

Question

All values of array $A are string the same length.
$A = Array
(
[0] => 03
[1] => 04
[2] => 05
[3] => 06
// [4] => 07 // "07" before "04" position
[4] => 04
[5] => 05
[6] => 06
// [8] => 07 // "07" before "08" position
[7] => 08
[8] => 03
[9] => 04
[10] => 05
[11] => 06
[12] => 07 // it is existing
[13] => 08
) ;
I want to Insert the "07" element if it is not existing before "04" or "08" position.start from position 1
So It will be after changed
$A = Array
(
[0] => 03
[1] => 04
[2] => 05
[3] => 06
[4] => 07 // just appended
[5] => 04
[6] => 05
[7] => 06
[8] => 07 // just append
[9] => 08
[10] => 03
[11] => 04
[12] => 05
[13] => 06
[14] => 07
[15] => 08
) ;
Anybody know how to do this ,help me please?

Answer 1

There would be "prettier" ways to do this but, as intended...
iterate the array
if the current value is equal to 7 minus 1 you will insert a new value there
create a function "insert_into_array" that:
a) Splits your array in two (look at array_chunk)
b) POPs your element to the end of the first array (array_pop)
c) merges your two arrays back (array_merge)
I've abstained from writing any code as this is probably homework and, writing code, even if you're not really deep thinking the problem will push you a long way to passing the exam...

Answer 2

not the most beautiful solution, but should do the job:
$b = array();
for($i=0;$i<count($A);$i++){
$b[] = $A[$i];
if(($i<count($A) - 1) && ($A[$i+1]<$A[$i] || ($A[$i+1] == '08')) && $A[$i] < '07')
$b[] = '07';
}
var_dump($b);

Answer 3

First, find the gaps in your array, that is the positions where there's 06 but not a following 07:
$positions = array();
foreach ($A as $k => $v) {
if (isset($last) && $last != $v - 1 && $last == '06') {
$positions[] = $k;
}
$last = $v;
}
Then, insert them:
$count = 0;
foreach ($positions as $pos) {
array_splice($A, $pos + ($count++), 0, '07');
}
That's it.

Answer 4

//make sure the array is numeric:
$A = array_values($A);
foreach(array('04','08') as $search){
$positions = array_keys($A,$search);
rsort($positions);
foreach($positions as $key){
if($key==0 || $A[$key-1] != '07'){
array_splice($A,$key,0,'O7');
}
}
}

Answer 5

In 2017, I've found 2 beautiful methods that is part of nette\utils package.
Arrays::insertBefore()
Arrays::insertAfter()
They do job perfectly!
Just run:
composer require nette/utils
and use Arrays class or inspire in their code.