更改引用后增加值不会增加两个值

Question

在 C++ 中更改引用的目标并增加初始值时，为什么 a 和 b 在以下示例中不相同：

输出：a = 11 / b = 10

using namespace std;

void SampleMethod(int& val)
{
    val++;
}

int main()
{
    int a = 5;
    int b = 10;

    int& ref = a;
    ref = b;

    SampleMethod(a);


    cout << "Result: " << endl << a << endl << b << endl;
    return 0;
}

这是一个工作示例：https://www.mycompiler.io/view/FVGKtQr

Answer 1

void SampleMethod(int& val)
{
    val++;
}

int main()
{
    int a = 5;
    int b = 10;

    int& ref = a; //ref bound to a and has a's value i.e. 5
    ref = b; // ref doesn't point to b now but just sets the value of a to 10

    SampleMethod(a); // a gets incremented inside the function and becomes 11


    cout << "Result: " << endl << a << endl << b << endl;
    return 0;
}

引用不跟踪 b，因此 b 不会将其值更改为 11。它类似于：

int* ref = &a;
*ref = b;

减轻这种可能的混淆，即引用可以设置为在初始化后跟踪另一个变量（他们不能！）的一种可能方法是使用花括号初始化器来初始化引用.所以

int& ref{a}; //Initializes reference and binds it to a
ref = b; // Changes the value of the underlying object (a) not setting it to b

Answer 2

changing the target of a reference

不可以，引用不能在初始化后重新绑定。然后

int& ref = a;     // bind ref to a, i.e. make ref an alias of a
ref = b;          // assign b to ref, as the effect the object bound by ref (i.e. a) is assigned from b with value 10

SampleMethod(a);  // a is incremented to 11, b is still 10

更改引用后增加值不会增加两个值

Increasing value after changing a references does not increase both values

c++

reference