c++11 extension and non-static data

I want to building my codes but I can't

#include <iostream>
using namespace std;

class CTestData {
public:

    explicit CTestData(int nParam) : m_nData(nParam) {  }

    operator int(void) { return m_nData; }
    int GetData() const { return m_nData; }
    void SetData(int nParam) { m_nData = nParam; }

private:
    int main(int argc, char* argv[]) {
    CTestData a(10);
    cout << a.GetData() << endl;
    cout << a << endl;
    cout << (int)a << endl;
    cout << static_cast<int>(a) << endl;

    return 0;
}
}

Here's my errors.

warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] ld: can't link with a main executable file '/Users/a1/C++/.vscode/autotype' for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation

and this is my tasks.json

{
  "version": "2.0.0",
  "runner": "terminal",
  "type": "shell",
  "echoCommand": true,
  "presentation" : { "reveal": "always" },
  "tasks": [
    //C++ 컴파일
    {
      "label": "build and compile for C++",
      "type": "shell",
      "command": "g++",
      "args": [
        "-g",
        "-o",
        "-std=c++14",
        "${fileDirname}/${fileBasenameNoExtension}",
        "${file}"

    ],
      "group": {
        "kind":"build",
      "isDefault": true },

      //컴파일시 에러를 편집기에 반영
      //참고:   https://code.visualstudio.com/docs/editor/tasks#_defining-a-problem-matcher

      "problemMatcher": {
          "fileLocation": [
              "relative",
              "${workspaceRoot}"
          ],
          "pattern": {
              // The regular expression. 
             //Example to match: helloWorld.c:5:3: warning: implicit declaration of function 'prinft'
              "regexp": "^(.*):(\\d+):(\\d+):\\s+(warning error):\\s+(.*)$",
              "file": 1,
              "line": 2,
              "column": 3,
              "severity": 4,
              "message": 5
          }
      }
  },
  //C 컴파일
  {
      "label": "save and compile for C",
      "command": "gcc",
      "args": [
          "${file}",
          "-o",
          "${fileDirname}/${fileBasenameNoExtension}"
      ],
      "group": {
        "kind":"build",
      "isDefault": true},

      //컴파일시 에러를 편집기에 반영
      //참고:   https://code.visualstudio.com/docs/editor/tasks#_defining-a-problem-matcher

      "problemMatcher": {
          "fileLocation": [
              "relative",
              "${workspaceRoot}"
          ],
          "pattern": {
              // The regular expression. 
             //Example to match: helloWorld.c:5:3: warning: implicit declaration of function 'prinft'
              "regexp": "^(.*):(\\d+):(\\d+):\\s+(warning error):\\s+(.*)$",
              "file": 1,
              "line": 2,
              "column": 3,
              "severity": 4,
              "message": 5
          }
      }
  },
  // 바이너리 실행(Ubuntu)

  {

      "label": "execute",

      "command": "cd ${fileDirname} && ./${fileBasenameNoExtension}",

      "group": "test"

      }

  ]
}

and this is my launch.json

{

"version": "0.2.0",
"configurations": [
    {
        "name": "(lldb) Launch",
        "type": "cppdbg",
        "request": "launch",
        "program": "enter program name, for example ${workspaceFolder}/a.out",
        "miDebuggerPath": "/Users/a1/C++/cpp.exe",
        "args": [],
        "stopAtEntry": false,
        "cwd": "${workspaceFolder}",
        "environment": [],
        "externalConsole": true,
        "MIMode": "lldb"
    }
]
}

this is my cpp_properties.json help me PLEASE :<

{
"configurations": [
    {
        "name": "Mac",
        "includePath": [
            "${workspaceFolder}"
        ],
        "defines": ["_DEBUG", "UNICODE"],
        "macFrameworkPath": [
            "/System/Library/Frameworks",
            "/Library/Frameworks"
        ],
        "compilerPath": "/Users/a1/C++/first.cpp",
        "cStandard": "c11",
        "cppStandard": "c++17",
        "intelliSenseMode": "clang-x64"
    }
],

"browse": {
    "path": [
        "${workspaceFolder}","/Users/a1/C++/first.cpp"
    ],
    "limitSymbolsToIncludedHeaders": true,
    "databaseFilename": ""
},

"version": 4
}