title: Incomplete type is not allowed (c++ VSCODE)
body: <p>I have simply created an Array <code>a</code> using container class. However, VScode's IntelliSense is showing an error. Here's an implementation of selection sort.</p>
  
  <p><a href="https://i.stack.imgur.com/hTxn4.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hTxn4.png" alt="![IntelliSense Error"></a></p>
  
  <p>the contents of the <code>c_cpp_properties.json</code> file are as follows</p>
  
  <pre><code>{
      "configurations": [
          {
              "name": "Win32",
              "includePath": [
                  "${workspaceFolder}/**"
              ],
              "defines": [
                  "_DEBUG",
                  "UNICODE",
                  "_UNICODE"
              ],
              "windowsSdkVersion": "10.0.16299.0",
              "compilerPath": "C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.13.26128/bin/Hostx64/x64/cl.exe",
              "cStandard": "c11",
              "cppStandard": "c++17",
              "intelliSenseMode": "msvc-x64"
          }
      ],
      "version": 4
  }
  </code></pre>
  
  <p>the code compiles and runs successfully. How do I fix the incorrect IntelliSense error?</p>