finished HelloWorld example.

src/TensorFlowNET.Core/APIs/tf.constant.cs

@@ -9,12 +9,12 @@ namespace Tensorflow
     {
         public static Tensor constant(NDArray nd, string name = "Const", bool verify_shape = false)
         {
-            //constant_op.Create(nd, name, verify_shape);
-            var graph = tf.get_default_graph();
+            var t = constant_op.Create(nd, name, verify_shape);
+            /*var graph = tf.get_default_graph();
             var tensor = new Tensor(nd);
-            var op = graph.NewOperation("Const", name, tensor);
+            var op = graph.NewOperation("Const", name, tensor);*/
             
-            return null;
+            return t;
         }
     }
 }

src/TensorFlowNET.Core/Graphs/Graph.Operation.cs

@@ -8,22 +8,22 @@ namespace Tensorflow
 {
     public partial class Graph
     {
-        public Operation NewOperation(string opType, string opName, Tensor tensor)
+        public OpDef GetOpDef(string type)
         {
-            var desc = c_api.TF_NewOperation(_handle, opType, opName);
-
-            if (tensor.dtype == TF_DataType.TF_STRING)
-            {
-                var value = "Hello World!";
-                var bytes = Encoding.UTF8.GetBytes(value);
-                var buf = Marshal.AllocHGlobal(bytes.Length + 1);
-                Marshal.Copy(bytes, 0, buf, bytes.Length);
-                c_api.TF_SetAttrString(desc, "value", buf, (uint)value.Length);
-            }
-            else
+            using (var buffer = new Buffer())
+            using (var status = new Status())
             {
-                c_api.TF_SetAttrTensor(desc, "value", tensor, Status);
+                c_api.TF_GraphGetOpDef(_handle, type, buffer, status);
+                return OpDef.Parser.ParseFrom(buffer.Data);
             }
+        }
+
+        public OperationDescription NewOperation(string opType, string opName)
+        {
+            OperationDescription desc = c_api.TF_NewOperation(_handle, opType, opName);
+            return desc;
+
+            /*c_api.TF_SetAttrTensor(desc, "value", tensor, Status);
             
             Status.Check();
 
@@ -32,7 +32,7 @@ namespace Tensorflow
             var op = c_api.TF_FinishOperation(desc, Status);
             Status.Check();
 
-            return op;
+            return op;*/
         }
     }
 }

src/TensorFlowNET.Core/Graphs/Graph.cs

@@ -106,9 +106,15 @@ namespace Tensorflow
                 original_op: null,
                 op_def: op_def);
 
+            _create_op_helper(op, true);
             return op;
         }
 
+        private void _create_op_helper(Operation op, bool compute_device = true)
+        {
+
+        }
+
         public void _add_op(Operation op)
         {
             _nodes_by_id[op._id] = op;

src/TensorFlowNET.Core/Operations/Operation.cs

@@ -109,12 +109,17 @@ namespace Tensorflow
             Graph = g;
 
             _id_value = Graph._next_id();
+            if(op_def == null)
+                op_def = g.GetOpDef(node_def.Op);
 
             _handle = ops._create_c_op(g, node_def, inputs);
-
+            
             _outputs = new Tensor[NumOutputs];
+            output_types = new TF_DataType[NumOutputs];
+
             for (int i = 0; i < NumOutputs; i++)
             {
+                output_types[i] = OutputType(i);
                 _outputs[i] = new Tensor(this, i, output_types[i]);
             }
 

src/TensorFlowNET.Core/Operations/c_api.ops.cs

@@ -197,7 +197,7 @@ namespace Tensorflow
         public static extern int TF_OperationOutputListLength(IntPtr oper, string arg_name, IntPtr status);
 
         [DllImport(TensorFlowLibName)]
-        public static extern void TF_SetAttrValueProto(IntPtr desc, string attr_name, IntPtr proto, UIntPtr proto_len, IntPtr status);
+        public static extern void TF_SetAttrValueProto(IntPtr desc, string attr_name, IntPtr proto, uint proto_len, IntPtr status);
 
         /// <summary>
         /// Set `num_dims` to -1 to represent "unknown rank".

src/TensorFlowNET.Core/Operations/ops.cs

@@ -25,17 +25,17 @@ namespace Tensorflow
 
         public static unsafe IntPtr _create_c_op(Graph graph, NodeDef node_def, List<Tensor> inputs)
         {
-            var op_desc = c_api.TF_NewOperation(graph, node_def.Op, node_def.Name);
+            var op_desc = graph.NewOperation(node_def.Op, node_def.Name);
 
             // Add inputs
             if(inputs != null && inputs.Count > 0)
             {
-                foreach (var op_input in inputs)
+                /*foreach (var op_input in inputs)
                 {
                     c_api.TF_AddInput(op_desc, op_input._as_tf_output());
-                }
+                }*/
 
-                //c_api.TF_AddInputList(op_desc, inputs.Select(x => x._as_tf_output()).ToArray(), inputs.Count);
+                c_api.TF_AddInputList(op_desc, inputs.Select(x => x._as_tf_output()).ToArray(), inputs.Count);
             }
 
             var status = new Status();
@@ -48,9 +48,10 @@ namespace Tensorflow
                 var bytes = attr.Value.ToByteArray();
                 var proto = Marshal.AllocHGlobal(bytes.Length);
                 Marshal.Copy(bytes, 0, proto, bytes.Length);
-                c_api.TF_SetAttrValueProto(op_desc, attr.Key, proto, proto_len: (UIntPtr)bytes.Length, status: status);
+                
+                c_api.TF_SetAttrValueProto(op_desc, attr.Key, proto, proto_len: (uint)bytes.Length, status: status);
 
-                if(status.Code != TF_Code.TF_OK) throw new Exception(status.Message);
+                status.Check(true);
             }
 
             var c_op = c_api.TF_FinishOperation(op_desc, status);
@@ -60,6 +61,11 @@ namespace Tensorflow
             return c_op;
         }
 
+        public static OpDef _get_op_def(Graph graph, string type)
+        {
+            return graph.GetOpDef(type);
+        }
+
         public static NodeDef _NodeDef(string op_type, string name, string device = "", Dictionary<string, AttrValue> attrs = null)
         {
             var node_def = new node_def_pb2.NodeDef();

src/TensorFlowNET.Core/Sessions/BaseSession.cs

@@ -115,12 +115,27 @@ namespace Tensorflow
                 run_metadata: IntPtr.Zero,
                 status: status);
 
-            var result = output_values.Select(x => c_api.TF_TensorData(x))
-                .Select(x => (object)*(float*)x)
-                .ToArray();
+            object[] result = new object[fetch_list.Length];
 
-            var op = new Operation(fetch_list[0].oper);
-            //var metadata = c_api.TF_OperationGetAttrMetadata(fetch_list[0].oper, "dtype", status);
+            for (int i = 0; i < fetch_list.Length; i++)
+            {
+                var tensor = new Tensor(output_values[i]);
+                
+                switch (tensor.dtype)
+                {
+                    case TF_DataType.TF_STRING:
+                        // wired, don't know why we have to start from offset 9.
+                        var bytes = tensor.Data();
+                        result[i] = UTF8Encoding.Default.GetString(bytes, 9, bytes.Length - 9);
+                        break;
+                    case TF_DataType.TF_FLOAT:
+                        result[i] = *(float*)c_api.TF_TensorData(output_values[i]);
+                        break;
+                    default:
+                        throw new NotImplementedException("can't get output");
+                        break;
+                }
+            }
 
             return result;
         }

src/TensorFlowNET.Core/Status/Status.cs

@@ -8,7 +8,7 @@ namespace Tensorflow
     /// TF_Status holds error information. It either has an OK code, or
     /// else an error code with an associated error message.
     /// </summary>
-    public class Status
+    public class Status : IDisposable
     {
         private readonly IntPtr _handle;
 

src/TensorFlowNET.Core/Tensors/Tensor.cs

@@ -146,7 +146,6 @@ namespace Tensorflow
         {
             var data = new byte[bytesize];
             Marshal.Copy(buffer, data, 0, (int)bytesize);
-
             return data;
         }
 

src/TensorFlowNET.Core/Tensors/constant_op.cs

@@ -22,17 +22,21 @@ namespace Tensorflow
         public static Tensor Create(NDArray nd, string name = "Const", bool verify_shape = false)
         {
             Graph g = ops.get_default_graph();
-            var tensor_value = new AttrValue();
             var tensor_pb = tensor_util.make_tensor_proto(nd, verify_shape);
-            tensor_value.Tensor = tensor_pb;
+            var tensor_value = new AttrValue
+            {
+                Type = tensor_pb.Dtype,
+                Tensor = tensor_pb
+            };
+            
             var dtype_value = new AttrValue
             {
                 Type = tensor_value.Tensor.Dtype,
             };
 
             var attrs = new Dictionary<string, AttrValue>();
-            attrs["dtype"] = dtype_value;
             attrs["value"] = tensor_value;
+            attrs["dtype"] = dtype_value;
 
             var op = g.create_op("Const",
                 null,

src/TensorFlowNET.Core/Tensors/tensor_util.cs

@@ -2,6 +2,7 @@
 using NumSharp.Core.Interfaces;
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 using tensor_pb2 = Tensorflow;
 
@@ -32,7 +33,7 @@ namespace Tensorflow
                     tensor_proto.DoubleVal.AddRange(nd.Data<double>());
                     break;
                 case "String":
-                    tensor_proto.StringVal.Add(Google.Protobuf.ByteString.CopyFrom(nd.Data<string>()[0], Encoding.UTF8));
+                    tensor_proto.StringVal.AddRange(nd.Data<string>().Select(x => Google.Protobuf.ByteString.CopyFromUtf8(x)));
                     break;
                 default:
                     throw new Exception("Not Implemented");