How to Calculate the Distance Between Two Zip Codes in PHP?

Calculating Distance Between Zip Codes in PHP

Calculating the distance between two zip codes requires accessing a database containing latitude and longitude information for each zip code. This question explores how to compute this distance using data from a MySQL table.

SOLUTION

The suggested solution leverages a PHP function to calculate the distance between two points given their latitudes and longitudes. Here's the code:

<code class="php">function calc_distance($point1, $point2)
{
    // Constants
    $radius       = 3958;      // Earth's radius (miles)
    $deg_per_rad  = 57.29578;  // Number of degrees/radian (for conversion)

    $distance = ($radius * pi() * sqrt(
        ($point1['lat'] - $point2['lat'])
        * ($point1['lat'] - $point2['lat'])
        + cos($point1['lat'] / $deg_per_rad)  // Convert to radians for cos()
        * cos($point2['lat'] / $deg_per_rad)  // Convert to radians for cos()
        * ($point1['long'] - $point2['long'])
        * ($point1['long'] - $point2['long'])
    ) / 180);

    return $distance;  // Returned using the units used for $radius.
}</code>

USAGE

This function requires two data points ($point1 and $point2) as parameters, each containing the latitude and longitude of a zip code. The returned distance will be in the same units as the radius constant provided (miles in this case).

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