C++ 变量、常量、指针基本引用方法（三）

#include 
using namespace std;

void test02(int& c, int& d);

void test01() {
    //普通变量引用
    int a = 10;
    int& b = a;
    //int*b=&a;
    
    cout << "b=" << b << endl;
    //cout <<"b=" << *b << endl;
    cout <<"a=" << a << endl;

    //常量引用
    const int num = 20;
    int* pnum = (int*)#
    *pnum = 200;
    cout<<"num=" << num << endl;

    //数组引用
    int arr[10];
    int (&pArr)[10]=arr;
    //int* pArr=arr;
    for (int i = 0;i<10;i++) {
        pArr[i] = (i + 1) * 2;
        cout <<"ar[i] = " << arr[i] << endl;
    }

    //参数传递
    int c = 10;
    int d = 20;
    test02(c,d);
    cout << "c =" << c << " d=" << d << endl;
}

void test02(int& c, int& d) {
    int temp = c;
    c = d;
    d = temp;
}

//void test02(int *c,int *d){
//    int temp=*c;
//    *c=*d;
//    *d=temp;
//}

//函数返回引用
int& fun1() {
    int a = 10;
    return a;
    //第二次访问a的值会被释放掉
}

int& fun2() {
    static int a = 10;
    return a;
}

void test03() {
    int& f1 = fun1();
    cout << "f1=" << f1 << endl;
    cout << "f1=" << f1 << endl;

    int& f2 = fun2();
    cout << "f2=" << f2 << endl;
    cout << "f2=" << f2 << endl;

    fun2() = 100;
    cout << "f2=" << f2 << endl;
    cout << "f2=" << f2 << endl;
}

//指针引用
struct Person {
    int id;
};

//void allocateSpace(Person **p) {
//    *p = new Person();
//    (*p)->id = 20;
//}

void allocateSpace(Person*& p) {
    p = new Person();
    p->id = 20;
}

void test04() {
    Person* p = NULL;
    //allocateSpace(&p);
    allocateSpace(p);

    cout << "p.age = " << p->id << endl;
    delete p;
}

int main()
{
    test01();
    test03();
    test04();
    system("pause");
    return EXIT_SUCCESS;
}