Reading from a file into an associative array - php

Question

I have to create a page, where the user is able to search a suburb and the page will print the postcode of that suburb.
I am having a little difficulty with putting the data from the .txt document into the variables for the associative array.
Thanks for your help.
This is what I have so far.
<?php
$file = "postcode.txt";
$handle = fopen($file, 'r');
$postcodearray = file($file);
$suburb = explode(",", );
$postcodearray[$suburb] = $postcode;
fclose($handle)
?>
and this is the format of the .txt document...
3000,MELBOURNE
3001,MELBOURNE
3002,EAST MELBOURNE
3003,WEST MELBOURNE
etc.

Answer 1

$postcodearray = file($file);
foreach($postcodearray as $pca){
$p_codes=explode(',',$pca);
$postcodearray2[$p_codes[1]] = $p_codes[0];
}
print_r($postcodearray2);

Answer 2

I prefer file_get_contents when working with files
<?php
$content = file_get_contents('postcode.txt');
$rows = explode("\n", $content);
$data = [];
foreach ($rows as $row) {
$columns = explode(',', $row);
$data[$columns[0]] = $columns[1];
}

Answer 3

An alternative array would group MELBOURNE EAST and WEST in one array with subarrays. (Look at the output, I don't know how to explain it)
I explode MELBOURNE EAST on space and use EAST as a key in the array.
// Replace this line with file_get_contents("postcode.txt");
$txt = "3000,MELBOURNE
3001,MELBOURNE
3002,EAST MELBOURNE
3003,WEST MELBOURNE
3603,WEST SYDNEY
3103,NORTH PERTH";
$rows = explode(PHP_EOL, $txt);
$arr= [];
foreach($rows as $row){
List($postcode, $suburb) = explode(",", $row);
If(in_array(substr($suburb,0,4), array("EAST", "WEST")) || in_array(substr($suburb,0,5), array("SOUTH", "NORTH"))){
// If the suburb includes a direction explode it to temp.
$temp = explode(" ", $suburb);
$arr[$temp[1]][$temp[0]][] = $postcode;
}else{
// If there is no direction just save it as suburb "main"
$arr[$suburb][] = $postcode;
}
}
Var_dump($arr);
https://3v4l.org/RXgSR
Output:
array(3) {
["MELBOURNE"]=>
array(4) {
[0]=>
string(4) "3000"
[1]=>
string(4) "3001"
["EAST"]=>
array(1) {
[0]=>
string(4) "3002"
}
["WEST"]=>
array(1) {
[0]=>
string(4) "3003"
}
}
["SYDNEY"]=>
array(1) {
["WEST"]=>
array(1) {
[0]=>
string(4) "3603"
}
}
["PERTH"]=>
array(1) {
["NORTH"]=>
array(1) {
[0]=>
string(4) "3103"
}
}
}