《C++游戏编程入门》第7章 指针：Tic-Tac-Toe 2.0

7.1 指针基础

包含内存地址的变量。

07.pointing.cpp

#include <iostream>
#include <string>
using namespace std;

int main()
{
   
    int *pAPointer; // 声明指针

    int *pScore = nullptr; // 声明并初始化指针，空指针

    int score = 1000;
    pScore = &score; // 地址赋值给指针

    cout << "Assigning &score to pScore\n";
    cout << "&score is: " << &score << "\n"; // address of score variable
    cout << "pScore is: " << pScore << "\n"; // address stored in pointer
    cout << "score is: " << score << "\n";
    cout << "*pScore is: " << *pScore << "\n\n"; // 指针解引用

    cout << "Adding 500 to score\n";
    score += 500;
    cout << "score is: " << score << "\n";
    cout << "*pScore is: " << *pScore << "\n\n";

    cout << "Adding 500 to *pScore\n";
    *pScore += 500;
    cout << "score is: " << score << "\n";
    cout << "*pScore is: " << *pScore << "\n\n";

    cout << "Assigning &newScore to pScore\n";
    int newScore = 5000;
    pScore = &newScore; // 指针重新赋值
    cout << "&newScore is: " << &newScore << "\n";
    cout << "pScore is: " << pScore << "\n";
    cout << "newScore is: " << newScore << "\n";
    cout << "*pScore is: " << *pScore << "\n\n";

    cout << "Assigning &str to pStr\n";
    string str = "score";
    string *pStr = &str; // 对象指针
    cout << "str is: " << str << "\n";
    cout << "*pStr is: " << *pStr << "\n";
    cout << "(*pStr).size() is: " << (*pStr).size() << "\n";
    cout << "pStr->size() is: " << pStr->size() << "\n";

    return 0;
}

7.2 指针和常量

const用来限制指针。

• 常量指针

int score = 100;
int* const pScore = &score;//常量指针，必须声明时初始化，指向地址固定
*pScore = 500;//可修改指向的值

• 指向常量的指针（指针常量）

const int* pNumber;//int const * pNumber;
int one = 1;
pNumber = &one;//可指向常量或非常量，指向的值是常量（无法通过指针修改）
int two = 2;
pNumber = &tow;//指向地址可改变
//*pNumber = 3;//error，指向的值不可改变

• 指向常量的常量指针（常量引用）

int N = 5;
//const int const * pBound = &N;
//声明时初始化，指向地址固定，指向的值固定
//可指向常量或非常量，指向的值是常量（无法通过指针修改）
const int* const pBound = &N;

7.3 传递指针

传址调用。

07.swap_pointer_ver.cpp

#include <iostream>
using namespace std;

void badSwap(int x, int y);
void goodSwap(int *const pX, int *const pY); // 常量指针，指向地址固定，指向的值可修改

int main()
{
   
    int myScore = 150;
    int yourScore = 1000;
    cout << "Original values\n";
    cout << "myScore: " << myScore << "\n";
    cout << "yourScore: " << yourScore << "\n\n";

    cout << "Calling badSwap()\n";
    badSwap(myScore, yourScore);
    cout << "myScore: " << myScore << "\n";
    cout << "yourScore: " << yourScore << "\n\n";

    cout << "Calling goodSwap()\n";
    goodSwap(&myScore, &yourScore);
    cout << "myScore: " << myScore << "\n";
    cout << "yourScore: " << yourScore << "\n";

    return 0;
}

void badSwap(int x, int y)
{
   
    int temp = x;
    x = y;
    y = temp;
}

void goodSwap(int