Calculate distances using Google Maps

I am creating a business directory website which has street addresses stor开发者_StackOverflowed in the database. I would like to calculate the distance from a given zipcode to the street address using google maps in ASP.Net. I don't even know where to begin. Can someone please help?

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please see the links below

http://briancray.com/2009/04/01/how-to-calculate-the-distance-between-two-addresses-with-javascript-and-google-maps-api/

http://briancray.com/2009/06/23/calculate-driving-distance-google-maps-api/

http://www.ehow.com/how_5142324_calculate-distance-google-maps.html