Namespace and pointer in cpp

18 Mar 2024

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Use pointer to creat and access nested class or struct instance.

#include <iostream>
#include <vector>
#include <memory>

class A
{
public:
    typedef std::shared_ptr<A> Ptr;
    
    struct ASub
    {
    public:
        typedef std::shared_ptr<ASub> Ptr;
        int x_;
        
        ASub(int x);
    };
    
    int x_;
    Ptr a_ptr_;
    ASub::Ptr a_sub_ptr_;
    
    A(int x);
};

A::A(int x):x_(x){}
A::ASub::ASub(int x):x_(x){}

int main()
{
    A::Ptr a_ptr(new A(95479));
    std::cout << a_ptr->x_ << std::endl;
    a_ptr->a_sub_ptr_.reset(new A::ASub(23));
    std::cout << a_ptr->a_sub_ptr_->x_ << std::endl;
    
}

Output:

95479
23

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cpp online compiler: Coliru online compiler

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