从 C++ 常见问题精简版 -

Use references when you can, and pointers when you have to. References are usually preferred over pointers whenever you don't need "reseating". This usually means that references are most useful in a class's public interface. References typically appear on the skin of an object, and pointers on the inside. The exception to the above is where a function's parameter or return value needs a "sentinel" reference — a reference that does not refer to an object. This is usually best done by returning/taking a pointer, and giving the NULL pointer this special significance (references must always alias objects, not a dereferenced NULL pointer). Note: Old line C programmers sometimes don't like references since they provide reference semantics that isn't explicit in the caller's code. After some C++ experience, however, one quickly realizes this is a form of information hiding, which is an asset rather than a liability. E.g., programmers should write code in the language of the problem rather than the language of the machine.

复制自wiki-

A consequence of this is that in many implementations, operating on a variable with automatic or static lifetime through a reference, although syntactically similar to accessing it directly, can involve hidden dereference operations that are costly. References are a syntactically controversial feature of C++ because they obscure an identifier's level of indirection; that is, unlike C code where pointers usually stand out syntactically, in a large block of C++ code it may not be immediately obvious if the object being accessed is defined as a local or global variable or whether it is a reference (implicit pointer) to some other location, especially if the code mixes references and pointers. This aspect can make poorly written C++ code harder to read and debug (see Aliasing).

我完全同意这一点，这就是为什么我认为只有在你有充分理由的时候才应该使用推荐信。

我的经验法则是:

Use pointers for outgoing or in/out parameters. So it can be seen that the value is going to be changed. (You must use &) Use pointers if NULL parameter is acceptable value. (Make sure it's const if it's an incoming parameter) Use references for incoming parameter if it cannot be NULL and is not a primitive type (const T&). Use pointers or smart pointers when returning a newly created object. Use pointers or smart pointers as struct or class members instead of references. Use references for aliasing (eg. int &current = someArray[i])

无论您使用哪一种，如果参数不明显，请不要忘记记录函数及其参数的含义。

“尽可能使用参考文献”规则有问题，如果你想保留参考文献供进一步使用，就会出现这种问题。为了举例说明这一点，假设您有以下类。

class SimCard
{
    public:
        explicit SimCard(int id):
            m_id(id)
        {
        }

        int getId() const
        {
            return m_id;
        }

    private:
        int m_id;
};

class RefPhone
{
    public:
        explicit RefPhone(const SimCard & card):
            m_card(card)
        {
        }

        int getSimId()
        {
            return m_card.getId();
        }

    private:
        const SimCard & m_card;
};

乍一看，通过引用传递RefPhone(const SimCard & card)构造函数中的形参似乎是个好主意，因为它可以防止向构造函数传递错误/空指针。它以某种方式鼓励在堆栈上分配变量，并从RAII中获益。

PtrPhone nullPhone(0);  //this will not happen that easily
SimCard * cardPtr = new SimCard(666);  //evil pointer
delete cardPtr;  //muahaha
PtrPhone uninitPhone(cardPtr);  //this will not happen that easily

但是暂时的事情会摧毁你的幸福世界。

RefPhone tempPhone(SimCard(666));   //evil temporary
//function referring to destroyed object
tempPhone.getSimId();    //this can happen

因此，如果你盲目地坚持引用，你就在传递无效指针的可能性与存储已销毁对象引用的可能性之间进行了权衡，这基本上是相同的效果。

edit:请注意，我坚持了这条规则:“尽可能使用引用，必须使用指针。”避免指针，直到你做不到为止。”这是被点赞最多、接受度最高的答案(其他答案也这么认为)。虽然这应该是显而易见的，但例子并不表明引用是不好的。然而，它们也可能被滥用，就像指针一样，它们也会给代码带来威胁。

指针和引用之间有以下区别。

当涉及到传递变量时，按引用传递看起来像按值传递，但具有指针语义(充当指针)。 引用不能直接初始化为0 (null)。 引用(引用，未引用对象)不能修改(相当于“* const”指针)。 Const引用可以接受临时形参。 局部const引用延长了临时对象的生存期

考虑到这些因素，我目前的规则如下。

Use references for parameters that will be used locally within a function scope. Use pointers when 0 (null) is acceptable parameter value or you need to store parameter for further use. If 0 (null) is acceptable I am adding "_n" suffix to parameter, use guarded pointer (like QPointer in Qt) or just document it. You can also use smart pointers. You have to be even more careful with shared pointers than with normal pointers (otherwise you can end up with by design memory leaks and responsibility mess).

在我的实践中，我个人确定了一个简单的规则——对可复制/可移动的原语和值使用引用，对具有长生命周期的对象使用指针。

对于Node的例子，我肯定会使用

AddChild(Node* pNode);

从 C++ 常见问题精简版 -

Use references when you can, and pointers when you have to. References are usually preferred over pointers whenever you don't need "reseating". This usually means that references are most useful in a class's public interface. References typically appear on the skin of an object, and pointers on the inside. The exception to the above is where a function's parameter or return value needs a "sentinel" reference — a reference that does not refer to an object. This is usually best done by returning/taking a pointer, and giving the NULL pointer this special significance (references must always alias objects, not a dereferenced NULL pointer). Note: Old line C programmers sometimes don't like references since they provide reference semantics that isn't explicit in the caller's code. After some C++ experience, however, one quickly realizes this is a form of information hiding, which is an asset rather than a liability. E.g., programmers should write code in the language of the problem rather than the language of the machine.