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   "source": [
    "[this doc on github](https://github.com/dotnet/interactive/tree/main/samples/notebooks/csharp/Docs)\n",
    "\n",
    "# Displaying output in a .NET notebook"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "When writing C# in a .NET notebook, the C# scripting language is used, which you might be familiar with from using the C# Interactive window in Visual Studio. This dialect of C# allows you to end a code submission without a semicolon, which tells C# scripting to return the value of the expression."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "dotnet_interactive": {
     "language": "csharp"
    }
   },
   "outputs": [],
   "source": [
    "var x = \"Hello!\";\n",
    "display(x);\n",
    "x"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "When you end a cell with an expression evaluation like this, it is the return value of the cell. There can only be a single return value for a cell. If you add more code after a return value expression, you'll see a compile error.\n",
    "\n",
    "There are also several ways to display information without using the return value. The most intuitive one for many .NET users is to write to the console:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "dotnet_interactive": {
     "language": "csharp"
    }
   },
   "outputs": [],
   "source": [
    "Console.Write(\"hello\");\n",
    "Console.Write(\" \");\n",
    "Console.WriteLine(\"world\");"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "But a more familiar API for many notebook users would be the `display` method."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "dotnet_interactive": {
     "language": "csharp"
    }
   },
   "outputs": [],
   "source": [
    "display(\"hello\");\n",
    "display(\"world\");"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Each call to `display` writes an additional display data value to the notebook.\n",
    "You can also update an existing displayed value by calling `Update` on the object returned by a call to `display`.\n",
    "\n",
    "Note, in some environments such as Jupyter Lab, only calls to `Update` executed during the execution of the cell are respected."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "dotnet_interactive": {
     "language": "csharp"
    }
   },
   "outputs": [],
   "source": [
    "var fruitOutput = display(\"Let's get some fruit!\");\n",
    "var basket = new [] {\"apple\", \"orange\", \"coconut\", \"pear\", \"peach\"};\n",
    "\n",
    "foreach (var fruit in basket)\n",
    "{\n",
    "    System.Threading.Thread.Sleep(1000);\n",
    "    fruitOutput.Update($\"I have 1 {fruit}.\");    \n",
    "}\n",
    "\n",
    "System.Threading.Thread.Sleep(1000);\n",
    "\n",
    "fruitOutput.Update(basket);"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "---\n",
    "**_See also_**\n",
    "* [Formatting outputs](Formatting-outputs.ipynb)\n",
    "* [HTML](HTML.ipynb)"
   ]
  }
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