Find closest longitude and latitude in array?

Question

I have a longitude and latitude as a string in PHP like below

49.648881
-103.575312

And I want to take that and look in an array of values

Answer 1

Iterate through the array, comparing values to what you have. If the value is smaller than your currently stored value (or if you don't have a currently stored value), store that value instead, otherwise throw it away.

$closest = null;
foreach($array as $key => $value){
    $distance = //compare distance here;
    if ($closest === null || $closest > $distance) {
        $closest = $distance;
    };
};

Of course, this will be made more difficult by the fact that latitude and longitude are on a sphere, and longitudes 179 and -179 are closer than 90 and 179.