C# example to use form recognizer api.

dotnet/FormRecognizer/CSHttpClientSample.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.2</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="12.0.2" />
+  </ItemGroup>
+
+</Project>

dotnet/FormRecognizer/Program.cs

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+using System;
+using System.Net.Http.Headers;
+using System.Net.Http;
+using System.Web;
+using System.IO;
+using Newtonsoft.Json.Linq;
+
+
+namespace CSHttpClientSample
+{
+    static class Program
+    {
+        static void Main()
+        {
+            MakeRequest();
+            Console.WriteLine("Please wait for the results to appear...");
+            Console.ReadLine();
+        }
+
+        static async void MakeRequest() // Extract values from form 
+        {
+            var client = new HttpClient();
+            var queryString = HttpUtility.ParseQueryString(string.Empty);
+            string fileLoc = @"path\FileName.pdf";
+            string contentType = "application/pdf";
+
+            // Request headers
+            client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", "Subsciption key");
+
+            // Request parameters
+            //queryString["keys"] = "test";
+            var uri = "https://westus2.api.cognitive.microsoft.com/formrecognizer/v1.0-preview/custom/<modelID>/ff956100-613b-40d3-ae74-58e4fcc76384/analyze?" + queryString;
+
+            HttpResponseMessage response;
+
+            // Request body
+            byte[] byteData = GetFileAsByteArray(fileLoc);
+
+            using (var content = new ByteArrayContent(byteData))
+            {
+                content.Headers.ContentType = new MediaTypeHeaderValue(contentType);
+                response = await client.PostAsync(uri, content);
+
+                // Asynchronously get the JSON response.
+                string contentString = await response.Content.ReadAsStringAsync();
+
+                // Display the JSON response.
+                Console.WriteLine("\nResponse:\n\n{0}\n", JToken.Parse(contentString).ToString());
+            }
+
+        }
+
+        /// <summary>
+        /// Returns the contents of the specified file as a byte array.
+        /// </summary>
+        /// <param name="imageFilePath">The image file to read.</param>
+        /// <returns>The byte array of the image data.</returns>
+        static byte[] GetFileAsByteArray(string imageFilePath)
+        {
+            // Open a read-only file stream for the specified file.
+            using (FileStream fileStream =
+                new FileStream(imageFilePath, FileMode.Open, FileAccess.Read))
+            {
+                // Read the file's contents into a byte array.
+                BinaryReader binaryReader = new BinaryReader(fileStream);
+                return binaryReader.ReadBytes((int)fileStream.Length);
+            }
+        }
+    }
+
+}