在C ++中使用私有类时未在此作用域错误中声明

Question

I've a class

class myClass
{
    private:

       std::list <myInnerClass> mylists;

       class myInnerClass
       {
            // Design for this private class
       }
}

I can't understand why the line std::list <myInnerClass> mylists gives me the following error:

  - Type 'myInnerClass' was not declared in this scope
  - Type 'myInnerClass' could not be resolved

Where am I wrong?

Answer 1

You use myInnerClass before you declare it.

This code will compile:

class myClass
{
    private:
       class myInnerClass
       {
            // Design for this private class
       }
       std::list <myInnerClass> mylists;
}

Answer 2

You are using your inner class before declaring it

fix:

   class myInnerClass
   {
        // Design for this private class
   };

   std::list <myInnerClass> mylists;

Answer 3

first you have to declare inner class and then You can use it

Your code

class myClass
{
private:
   std::list <myInnerClass> mylists;
   class myInnerClass
   {
        // Design for this private class
   }
}

Correct code:

class myClass
{
    private:
    class myInnerClass
       {
            // Design for this private class
       }
           std::list <myInnerClass> mylists;
    }