string json = "{\"uid\": \"xxxx\",\"pin\": \"xxxx\",\"source_id\": \"1270\",\"destination_id\": \"323\",\"date\": \"05-05-2017\"}";
var httpContent = new StringContent(json, Encoding.UTF8, "application/json");
using (var httpClient = new HttpClient())
{
var httpResponse = await httpClient.PostAsync("http://pudhukadai.co.in/api/bus/search_trip.php", httpContent);
if (httpResponse.Content != null)
{
var responseContent = await httpResponse.Content.ReadAsStringAsync();
}
}
and you may want to look at Newtonsoft.Json to handle creating the Json string.