How to reorder this array in a specific order? - php

Question

I have this string of random numbers that needs to have some of the integers converted into letters. Notice that it takes two positions in the string to make a letter.
01110413 Original string
This string should ultimately be converted into this:
A11D13 Converted string
Here is my code so far
$id = '01110413';
$chg = array(0 => array(0, 1), 3 => array(4, 5));
$ltr = array(00 => 'A', 01 => 'B', 03 => 'C', 04 => 'D');
$id = str_split($id);
foreach($chg as $ltrpos => $val){
// $ltrpos; letter position placement in string AFTER conversion to letter
$ltrkey = null;
foreach($val as $idkey){
$ltrkey .= $id[$idkey];
unset($id[$idkey]);
if(!empty($ltrkey)){
$out[$ltrpos] = $ltr[(INT)$ltrkey];
}
}
}
Running this code gives:
Array
(
[0] => B
[3] => D
)
I need to insert these new values in the place where the old integer values were. The $chg array key is the position where the values should be in the converted string.
How can I order my final $out array so that the integers that were unset are replaced with the converted letters in their place?

Answer 1

This should do it:
$id = '01110413';
// your string codes always take up two positions, so you just need to provide the final position in the string
$chg = array(0,3);
// You could actually change 00 to just 0 (since they're integers). Also, later in the script, the two character position is cast to an int, so it will match these values.
$ltr = array(00 => 'A', 01 => 'B', 03 => 'C', 04 => 'D');
$converted_id = doConvert($id, $ltr, $chg);
function doConvert($id, $conversion_codes, $final_position) {
if( count($final_position) == 0 ) return $id;
$next_pos = array_shift($final_position);
// convert the two characters at the next position to a letter
$id = substr($id, 0, $next_pos) . $conversion_codes[(int) substr($id, $next_pos, 2)] . substr($id, $next_pos+2); // (cast to an (int) so it will match the keys in our conversion array)
return doConvert($id, $conversion_codes, $final_position);
}
Output of this example is:
B11D13
You say the first value should be A, but 01 => B, that's why the first letter is B.

Answer 2

If every two characters in your original id is a code, you can use something more general, like this:
$id = '01110413';
$conversion = array('00' => 'A', '01' => 'B', '03' => 'C', '04' => 'D');
$converted_id = "";
for($i=0; $i < strlen($id); $i+=2) {
$char_code = substr($id, $i, 2);
// we don't know this code, just append it
if( empty($conversion[$char_code]) ) {
$converted_id .= $char_code;
}
// convert and append
else {
$converted_id .= $conversion[$char_code];
}
}