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 <?php function distance($lat1,$lng1,$lat2,$lng2) 
     { 
         // Convert degrees to radians. 
        $lat1=deg2rad($lat1); 
        $lng1=deg2rad($lng1); 
        $lat2=deg2rad($lat2); 
        $lng2=deg2rad($lng2); 
     
        // Calculate delta longitude and latitude. 
        $delta_lat=($lat2 - $lat1); 
        $delta_lng=($lng2 - $lng1); 
     
        return round( 6378137 * acos( cos( $lat1 ) * cos( $lat2 ) * cos( $lng1 - $lng2 ) + sin( $lat1 ) * sin( $lat2 ) ) ); 
     }