C++ 函数的返回值是引用

当函数返回值为引用时，若返回栈变量，不能成为其他引用的初始值，不能作为左值使用

若返回静态变量或全局变量，可以成为其他引用的初始值，即可作为右值使用，也可作为左值使用

//若返回静态变量或全局变量

//可以成为其他引用的初始值

//即可做右值，也可作为左值使用

#include<iostream>

using namespace std;

int getA()

{
            int a;

            a = 10;

            return a;
}

int& getA1()

{
            int a;

            a = 10;

            return a;
}

int getA4()

{
            int static b = 10;  //static的作用周期为整个程序的执行周期

            b++;

            return b;
}

int& getA3()

{
            int static b = 20;

            b++;

            return b;
}

int main()

{
            int a = getA();

            int a1 = getA1();

            int &a2 = getA1();

            cout <<"a=" <<a<< endl;                 //输出为10

            cout << "a1=" << a1 << endl;          //输出为10

            cout << "a2=" << a2 << endl;          //输出为乱码

            int b = 0;

            int b1 = 0;

            b = getA4();

            b1 = getA3();

            int &b2 = getA3();

            cout << "b=" << b << endl;                 //输出为11

            cout << "b1=" << b1 << endl;             //输出为21

            printf("b2=%d", b2);                              //输出为22

            system("pause");

}

/函数返回值为引用，可以做左值

#include<iostream>

using namespace std;

//返回的仅仅是一个值

int myget1()

{
            static int a=90;

            a++;

            return a;
}

//返回的是一个变量

int& myget2()

{
            static int b=40;

            b++;

            cout <<"b="<< b<< endl;

            return b;
}

int main()

{

            int c = 20;

            int b;

            int d;

            d = myget1();

            cout << "d="<<d<< endl;

            myget2() = 20;                              //函数返回值是引用，并且可以做左值

            b = myget2();                                //函数返回值是引用，并且可以做右值

            cout << "b="<<b<< endl;

            //cout << "myget2()="<<myget2()<< endl;

            system("pause");

}