https://qiita.com/ryuso/items/933d7183ba60ea443628#comment-e54add2af6af98c73cc4

object.cpp

#include <stdio.h>
#include <stdlib.h>
#include <iostream>

// 構造体はデータ定義。処理関数は別定義。他と同じ関数名にならないよう気を使う
typedef struct {
    const char *name;
} StructDrink;

void ask_more(StructDrink *drink) {
    std::cout << drink->name << "をもう一杯いかが？" << std::endl;
}


// クラスはデータ定義と処理関数が一体。他と同じ関数名でも別関数になる
class ClassDrink {
public:
    const char *name;

    ClassDrink(const char *name) {
        this->name = name;
    }

    void ask_more() {
        std::cout << this->name << "をもう一杯いかが？" << std::endl;
    }
};


void local_access() {
    StructDrink struct_drink = { .name = "コーラ" };
    ClassDrink class_drink = ClassDrink("コーヒー");

    std::cout << "local struct: " << struct_drink.name << std::endl;
    std::cout << "local class: " << class_drink.name << std::endl;
    ask_more(&struct_drink);
    class_drink.ask_more();
}

void object_access() {
    StructDrink *malloc_drink = (StructDrink *)malloc(sizeof(StructDrink));
    malloc_drink->name = "オレンジジュース";

    ClassDrink *instance_drink = new ClassDrink("バナナジュース");

    std::cout << "malloc object: " << malloc_drink->name << std::endl;
    std::cout << "instance object: " << instance_drink->name << std::endl;
    ask_more(malloc_drink);
    instance_drink->ask_more();

    free(malloc_drink);
    delete instance_drink;
}

int main()
{
    local_access();
    object_access();
}