c++ 靜態函數

 

//對象與對象之間的成員變量是相互獨立的.要想共用數據,則需要使用靜態成員或靜態方法
//#只要在類中聲明靜態成員變量,即使不定義對象,也可以為靜態成員變量分配空間,進而可以使用靜態成員變量.(因為靜態成員變量在對象創建之前就已經被分配了內存空間)
//#靜態成員變量雖然在類中,但它並不是隨對象的建立而分配空間的,也不是隨對象的撤銷而釋放(一般的成員在對象建立時會分配空間,在對象撤銷時會釋放).靜態成員變量是在程序編譯時分配空間,而在程序結束時釋放空間.
//#初始化靜態成員變量要在類的外面進行.初始化的格式如下:數據類型 類名::靜態成員變量名 = 初值;
//#不能用參數初始化表,對靜態成員變量進行初始化.
//#即可以通過類名來對靜態成員變量進行引用,也可以通過對象名來對靜態成員變量進行引用.

//普通成員函數和靜態成員函數的區別是:普通成員函數在參數傳遞時編譯器會隱藏地傳遞一個this指針.通過this指針來確定調用類產生的哪個對象;但是靜態成員函數沒有this指針,不知道應該訪問哪個對象中的數據,所以在程序中不可以用靜態成員函數訪問類中的普通變量.

#include <iostream>
using namespace std;
class CShop
{
public:
    CShop(int size);
    void ShowSize();
    static void ShowPrice(); //聲明靜態成員函數用來顯示價格
    static int ChangePrice(int price); //聲明靜態成員函數用來更改價格
private:
    int m_size; //聲明一個私有成員變量
    static int m_price; //聲明一個私有靜態成員變量
};
CShop::CShop(int size)
{
    m_size = size;
}

void CShop::ShowSize()
{
    cout << "商品數量:" << m_size << endl;
}
void CShop::ShowPrice()
{
    cout << "商品價格:" << m_price << endl;
}
int CShop::ChangePrice(int price)
{
    m_price = price;
    return m_price;
}
int CShop::m_price = 100; //初始化靜態成員變量
 
int main(int argc, char * argv[])
{
    CShop::ShowPrice();
    CShop::ChangePrice(200);
    CShop::ShowPrice();
    CShop shop(50);
 
    shop.ShowSize();
    shop.ShowPrice();
 
    return 0;
}

 

 

#include<iostream>
#include<string>
using namespace std;
class player {
    string playerName;  //玩家姓名
    int attack; //攻擊力
    int defense;  //防御力
    int health = 100;  //生命值 
    int maxHealth = 100; //最大生命值
public:
    static int playerNumber;
    //構造函數 總數+1
    player(int attackParam, int defenseParam, string nameParam) {
        attack = attackParam;
        defense = defenseParam;
        playerName = nameParam;
        ++playerNumber;
    }
    //析構 總數減1
    ~player() {
        --playerNumber;
    }
    //獲取攻擊力
    int getAttack() {
        return attack;
    }
    //設置攻擊力
    void setAttack(int attackParam) {
        attack = attackParam;
    }
    //獲取防御力
    int getDefense() {
        return defense;
    }
    //設置防御力
    void setDefense(int defenseParam) {
        defense = defenseParam;
    }
    //改變生命值
    void changeHealth(int healthParam) {
        health += healthParam;
        if (health > maxHealth)
        {
            health = maxHealth;
        }
        else if (health <= 0)
        {
            health = 0;
            cout << "Player " << playerName << "  is Dead ! " << endl;
            delete this;
        }
    }
    //顯示屬性
    void displayProperty() {
        cout << "名字：" << playerName << endl;
        cout << "攻擊力：" << attack << endl;
        cout << "防御力：" << defense << endl;
        cout << "生命值：" << health << endl;
    }
    void attackPlayer(player*  otherPlayer) {
        otherPlayer->changeHealth(-this->attack);
    }
    static int displayNumber() {
        cout << playerNumber << endl;
        return playerNumber;
    }
};
int player::playerNumber = 0;
int main() {
    player* player01 = new player(50, 50, "GSL");
    player* player02 = new player(70, 60, "LJL");
    player01->displayProperty();
    player02->displayProperty();
 
    if (player01)
    {
        player01->attackPlayer(player02);
    }
    if (player02)
    {
        player02->attackPlayer(player01);
    }
    cout << player::playerNumber << endl;
    if (player01)
    {
        player01->attackPlayer(player02);
    }
    if (player02)
    {
        player02->attackPlayer(player01);
    }
    cout << player::playerNumber << endl;
    system("pause");
    return 9696969;
}

 

https://blog.csdn.net/ttt301/article/details/52326067

https://blog.csdn.net/longyanbuhui/article/details/71404308