How to get latitude and longitude from address using C# or Javascript?

You can use Geocoding API of Google maps, here is the url format for it

https://maps.googleapis.com/maps/api/geocode/json?key=API-KEY&address=YourAddress&sensor=true

Now, suppose you need to convert "Address into Lat/long using C#", here is the method for it in C#

            var address = "SomeAddress";
             

            string url = "https://maps.googleapis.com/maps/api/geocode/json?key=APIKEY&address=" + address + "&sensor=true";

            var client = new RestClient(url);
            var request = new RestRequest(Method.GET);
            request.Timeout = 1000000;
            request.ReadWriteTimeout = 1000000;
            request.AddHeader("cache-control", "no-cache");
            request.AddHeader("content-type", "application/json");
            var response = client.Execute(request);
            JavaScriptSerializer oJS = new JavaScriptSerializer();
            oJS.MaxJsonLength = int.MaxValue;

            var oRootObject = oJS.Deserialize<MapsResponse.Rootobject>(response.Content);

            var markers = "[";
            markers += "{";
            markers += string.Format("'title': '{0}',", "Title Of marker");
            markers += string.Format("'lat': '{0}',", oRootObject.results[0].geometry.location.lat);
            markers += string.Format("'lng': '{0}',", oRootObject.results[0].geometry.location.lng);
            markers += string.Format("'description': '{0}'", "Description Here");
            markers += "},";
            markers += "]";

Your MapsResponse class would be as below

 public class MapsResponse
    {
        public class Rootobject
        {
            public Result[] results { get; set; }
            public string status { get; set; }
        }

        public class Result
        {
            public Address_Components[] address_components { get; set; }
            public string formatted_address { get; set; }
            public Geometry geometry { get; set; }
            public string place_id { get; set; }
            public string[] types { get; set; }
        }

        public class Geometry
        {
            public Location location { get; set; }
            public string location_type { get; set; }
            public Viewport viewport { get; set; }
        }

        public class Location
        {
            public float lat { get; set; }
            public float lng { get; set; }
        }

        public class Viewport
        {
            public Northeast northeast { get; set; }
            public Southwest southwest { get; set; }
        }

        public class Northeast
        {
            public float lat { get; set; }
            public float lng { get; set; }
        }

        public class Southwest
        {
            public float lat { get; set; }
            public float lng { get; set; }
        }

        public class Address_Components
        {
            public string long_name { get; set; }
            public string short_name { get; set; }
            public string[] types { get; set; }
        }

    }

In the above method string "markers" is a JSON string which contains list of address converted in Google map markers which has Lat/Long , Title and description data.

Now you can use "markers" JSON in your HTML view and use Javascript like below

<div id="dvMap" style="width: 500px; height: 500px">
</div>
    <script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?key=YourKEY"></script>

    <script type="text/javascript">
        //Get Markers from server in some way
        var markers = "MarkersJSON";
        function loadMap() {
            var mapOptions = {
                center: new google.maps.LatLng(markers[0].lat, markers[0].lng),
                zoom:15,
                mapTypeId: google.maps.MapTypeId.ROADMAP
            };
            var infoWindow = new google.maps.InfoWindow();
            var map = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
            for (i = 0; i < markers.length; i++) {
                var data = markers[i]
                var myLatlng = new google.maps.LatLng(data.lat, data.lng);
                var marker = new google.maps.Marker({
                    position: myLatlng,
                    map: map,
                    title: data.title
                });
                (function (marker, data) {
                    google.maps.event.addListener(marker, "click", function (e) {
                        infoWindow.setContent(data.description);
                        infoWindow.open(map, marker);
                    });
                })(marker, data);
            }
        }
        

    </script>

You need to provide "markers" JSON here by calling Ajax or in some other way, and do not forget to use your API-Key in the javascript also.