Study C++ Object life cycle

cppObjectLife.cpp

#include <stdio.h>
#include <iostream>
#include <memory>
#include <vector>

struct Tracer {     // ken: from book 'C++ Crash course' Page 97
private:
    const char* const _name;     // const xxx const mean cannot alter both address and content
public:
    Tracer(const char *name)
            : _name{name} {
        cout << name << " is constructed\n";
    }
    
    ~Tracer() {
        cout << _name << " is destructed\n";
    }
};


void pause() {
    cout << "Paused! press enter to continue\n";
    cin.ignore();           // Ref: https://stackoverflow.com/questions/903221/press-enter-to-continue
}


void testObjectCycle() {
    Tracer tracer("Tracer 1");

    std::vector<unique_ptr<Tracer>> tracerList1;
    std::vector<shared_ptr<Tracer>> tracerList2;
    
    //
    // pause();
    
    cout << "\nCreate an object inside a block scope\n";
    {
        Tracer tracerInBlock("Tracer in Block");
    }   // tracerInBlock is destructed here
    
    
    cout << "\nCreate an object pointer inside a block scope\n";
    {
        Tracer *trackerPtr = new Tracer("Tracer Raw Pointer");
    }   // trackerPtr not destructed here.. it is dangerous

    cout << "\nCreate an unqiue pointer inside a block scope\n";
    {
        unique_ptr<Tracer> uPtr = make_unique<Tracer>("Tracer Unique Pointer");
        //tracerList1.push_back(std::move(uPtr));     // this line make the sPtr destructed after pause
    }   // Cool, unique_ptr can be clean up when the block is ended

    cout << "\nCreate an shared pointer inside a block scope\n";
    {
        shared_ptr<Tracer> sPtr = make_shared<Tracer>("Tracer Shared Pointer");
        //tracerList2.push_back(sPtr);       // this line make the sPtr destructed after pause
    }   // Cool, shared_ptr can be clean up when the block is ended

    
    pause();
    cout << "Program End\n";
}

int main(int argc, char **argv)
{
  testObjectCycle();
}