cpp operator = aka assignment operator overload

//model/book.cpp
void book::operator=(const book &bk){
    std::cout<<std::endl<<std::endl<<std::endl<<"Called operator assignment overloaded!"
    <<std::endl<<std::endl<<std::endl;
    this->set_idx(bk.get_idx());
    this->set_id(bk.get_id());
    this->set_abstract(bk.get_abstract());
    this->set_author(bk.get_author());
    this->set_comment(bk.get_comment());
    this->set_content(bk.get_content());
    this->set_header(bk.get_header());
    this->set_isbn(bk.get_isbn());
    this->set_summary(bk.get_summary());
    this->set_title(bk.get_title());
    this->set_topic(bk.get_topic());
}

void book::print_book(const book&bk){
    std::cout<<std::fixed<<bk.get_idx()<<","<<bk.get_id()<<","<<bk.get_abstract()<<","<<bk.get_author()
    <<","<<bk.get_comment()<<","<<bk.get_content()<<","<<bk.get_header()<<","<<bk.get_isbn()<<","
    <<bk.get_summary()<<","<<bk.get_title()<<","<<bk.get_topic()<<std::endl;
}

//util.cpp
#include "util.h"

std::string util::get_time_now()
{
    std::chrono::high_resolution_clock::time_point now = std::chrono::high_resolution_clock::now();
    time_t raw_time = std::chrono::high_resolution_clock::to_time_t(now);
    struct tm tm_info = *std::localtime(&raw_time);
    std::chrono::milliseconds mills = std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch());
    std::chrono::seconds seconds = std::chrono::duration_cast<std::chrono::seconds>(now.time_since_epoch());
    uint64_t mills_count = mills.count() - seconds.count() * 1000;
    std::stringstream ss;
    ss << std::put_time(&tm_info, "%Y%m%d%H%M%S") << std::setfill('0') << std::setw(3) << mills_count;
    return ss.str();
}

std::string util::get_uuid()
{
    uuid_t new_uuid;
    char *uuid_value = (char *)malloc(40);
    uuid_generate(new_uuid);
    uuid_unparse(new_uuid, uuid_value);
    std::string dt_now(uuid_value);
    free(uuid_value);
    uuid_value = nullptr;
    return dt_now;
}

void util::print_log(std::string msg)
{
    std::cout << get_time_now() << ",finished in " << msg << std::endl;
}

void util::operator_override(){
    book bk(static_cast<uint64_t>(10*10),static_cast<uint64_t>(10*10),get_uuid(),get_uuid(),get_uuid(),
    get_uuid(),get_uuid(),get_uuid(),get_uuid(),get_uuid(),get_uuid());
    bk.print_book(bk);
    book another_book;
    another_book=bk;
    another_book.print_book(another_book);
    std::cout<<std::endl<<std::endl;
    std::cout<<"The original address "<<&bk<<std::endl;
    std::cout<<"The assigned address "<<&another_book<<std::endl;
    std::cout<<std::endl<<std::endl;
    std::stringstream ss;
    ss << __FUNCTION__ << "," << __LINE__ << std::endl;
    print_log(ss.str());
}

Compile

g++ -g -std=c++2a -I. *.cpp ./model/*.cpp -o h1 -luuid -lpthread

Run

When look into the above snapshot,it had invoked the overloaded assignment method and print the identical information.

But to my surprise,their addresses are different as below,think further,because they are different objects and called constructor respectively.