How to Calculate Distance Between Two Zip Codes in PHP?

Determining Distance Between Zip Codes in PHP

A user's request to calculate the distance between two zip codes necessitates utilizing a database of zip codes and their corresponding latitudes and longitudes. This guide provides a solution in PHP based on the provided data fields:

Solution:

To calculate the distance between two zip codes, the following steps can be taken:

1. Join the latitude and longitude values of the two zip codes using the defined database fields (LATITUDE and LONGITUDE) for each zip code.
2. Calculate the Haversine distance using the following formula:

<code class="php">function calc_distance($point1, $point2)
{
    $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'] / $deg_per_rad)  // Convert these to
                * cos($point2['lat'] / $deg_per_rad)  // radians for cos()
                * ($point1['long'] - $point2['long'])
                * ($point1['long'] - $point2['long'])
        ) / 180);

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

This code utilizes the Earth's radius constant (3958 miles) and converts the latitude and longitude values to radians for accurate distance calculation.

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