C++ Class with Pointer and Reference Example: GameTeam

[qingquan-li]

GameTeam/Player.h

#ifndef GAMETEAM_PLAYER_H
#define GAMETEAM_PLAYER_H

#include <string>
using namespace std;

class Player {
private:
    string  name;
    int score;
public:
    void setName(string);
    void setScore(int);
    string getName() const;
    int getScore() const;
};

#endif //GAMETEAM_PLAYER_H

GameTeam/Player.cpp

#include <string>
#include "Player.h"

using namespace std;

void Player::setName(string new_name) {
    name = new_name;
}

void Player::setScore(int new_score) {
    score = new_score;
}

string Player::getName() const {
    return name;
}

int Player::getScore() const {
    return score;
}

GameTeam/main.cpp

#include <iostream>
#include <string>
#include "Player.h"

using namespace std;

// Function prototypes
void printPlayerInfo(const Player&);
void changePlayer(Player&, string, int);
Player createPlayer(string, int);
Player* createPlayerWithPointer(string, int);

int main() {
    Player player1, player2;
    Player* player_ptr = nullptr;

    player1.setName("Alice");
    player1.setScore(50);
    printPlayerInfo(player1);

    changePlayer(player1, "Bob", 100);
    printPlayerInfo(player1);

    player2 = createPlayer("Jake", 200);
    printPlayerInfo(player2);

    player_ptr = createPlayerWithPointer("Jenny", 300);
    printPlayerInfo(*player_ptr);
    // Free dynamically allocated memory.
    // Avoid memory leaks (the value of the original memory space is accessed by other objects).
    delete player_ptr;
    // Make player_ptr a null pointer.
    // Avoid dangling pointer (the pointer pointing to an empty memory space).
    player_ptr = nullptr;

    return 0;
}

void printPlayerInfo(const Player& player) {
    cout << player.getName() << endl;
    cout << player.getScore() << endl;
}

void changePlayer(Player& p, string new_name, int new_score) {
    p.setName(new_name);
    p.setScore(new_score);
}

Player createPlayer(string new_name, int new_score) {
    Player p;
    p.setName(new_name);
    p.setScore(new_score);
    return p;
}

//Player* createPlayerWithPointer(string new_name, int new_score) {
//    Player p;
//    Player* p_ptr = &p;
//    p.setName(new_name);
//    p.setScore(new_score);
//    return p_ptr; // The address of the local variable may escape the function.
//    //  When the function ends, the address of the local variable (p) disappears.
//}

Player* createPlayerWithPointer(string new_name, int new_score) {
    Player* p_ptr = new Player;
    (*p_ptr).setName(new_name);   // p_ptr->setName(new_name);
    (*p_ptr).setScore(new_score); // p_ptr->setScore(new_score);
    return p_ptr;
}

Output:

Alice
50
Bob
100
Jake
200
Jenny
300