一听就懂：C++引用的具体应用

普通引用
1.做函数参数，替代指针
2.做函数的返回值
引用指针

 

#include <iostream>
using namespace std;
void mswap(int a, int b)
{
    int temp;
    temp = a;
    a = b;
    b = temp;
}
void mschange(int* pa, int* pb)
{
    int temp;
    temp = *pa;
    *pa = *pb;
    *pb = temp;
}
void msexchange(int& ma, int& mb)
{
    int temp;
    temp = ma;
    ma = mb;
    mb = temp;
}
/*
    引用的用途：
    普通引用
    1.做函数参数，替代指针
    2.做函数的返回值
    引用指针
*/
int getAge()
{
    int age = 18;
    return age;
}
int& getAge01()
{
    static int age = 18;//局部变量，函数调用结束内存会被释放
    return age;
}
void del(int* p)
{
    p = nullptr;
}
void del01(int*& p)
{
    p = nullptr;
}
int main()
{
    //1.普通引用
    //值传递不能交换两个变量的值
    int a = 2, b = 5;
    mswap(a, b);
    cout << a << " " << b << endl;;
    //地址传递可以交换两个变量的值
    mschange(&a, &b);
    cout << a << " " << b << endl;
    //引用也可以交换两个变量的值
    msexchange(a, b);
    cout << a << " " << b << endl;
    //引用做函数的返回值
    //getAge() = 20;//18=20 error
    cout << getAge() << endl;
    getAge01() = 22;
    cout << getAge01() << endl;
    //2.引用指针
    int* pNew = new int;
    del(pNew);
    cout << pNew << endl;
    del01(pNew);
    cout << pNew << endl;
    return 0;
}