New array from multidimensional array - url parsing - php

Question

I have the following URL: myexample.com/?city=Miami
and a large array (23k)
$e = $_GET["city"];
$myArray = array
(
array ("Miami","Florida"),
array ("Key West","Florida"),
array ("NOLA", "Luisiana"),
array ("Baton Rouge","Luisiana")
);
I'm looking for a solution to dynamically create a new array of cities that matches the state of the city in the URL, and echo all the cities from that state.
In other words:
if myexample.com/?city=NOLA, I would like to echo "Baton Rouge" and "NOLA" (from Luisiana)
if myexample.com/?city=Miami, echo "Key West" and "Miami" (from Florida)
etc.
There are quite a few similar questions answered already (here, here, but looping is not one of strengths (beginner).
Thank you.
EDIT1:
$resArray = array();
foreach($myArray as $arr) {
if(in_array($e, $arr))
$resArray[] = $arr;
}
print_r($resArray);
Result: Array ( [0] => Array ( [0] => Miami [1] => Florida ) )

Answer 1

First of all I would restructure your myArray in something like the following:
$stateAndCities = [
"Florida" => ["Miami","Key West"],
"Luisiana" => ["NOLA", "Baton Rouge"]
];
after that you can better handle the input and give an easier output
$city = $_GET["city"];
$resultCities = [];
$resultState = "";
// Loop over all states with their cities
foreach($stateAndCities as $state => $cities) {
if(in_array($city, $cities)){ // if the given $city is in the $cities?
$resultCities = $cities;
$resultState = $state;
break;
}
}
if(!empty($resultState) && !empty($resultCities)){ // ensure that the city was found in any state
echo $resultState;
print_r($resultCities);
}
(the code is not tested!)
Manual:
http://php.net/in_array
http://php.net/empty