C ++超类构造函数调用规则 [英] C++ superclass constructor calling rules

问题描述

什么是C ++规则从子类调用超类构造函数？

What are the C++ rules for calling the superclass constructor from a subclass one??

例如，我知道在Java中，你必须做为子类构造函数的第一行（如果你不隐式调用一个无arg超

For example I know in Java, you must do it as the first line of the subclass constructor (and if you don't an implicit call to a no-arg super constructor is assumed - giving you a compile error if that's missing).

推荐答案

基类构造函数会自动调用，如果他们有没有参数。如果要调用具有参数的超类构造函数，则必须使用子类的构造函数初始化列表。与Java不同，C ++支持多重继承（更好或更坏），因此基类必须以名称而不是super（）引用。

Base class constructors are automatically called for you if they have no argument. If you want to call a superclass constructor with an argument, you must use the subclass's constructor initialization list. Unlike Java, C++ supports multiple inheritance (for better or worse), so the base class must be referred to by name, rather than "super()".

class SuperClass
{
    public:

        SuperClass(int foo)
        {
            // do something with foo
        }
};

class SubClass : public SuperClass
{
    public:

        SubClass(int foo, int bar)
        : SuperClass(foo)    // Call the superclass constructor in the subclass' initialization list.
        {
            // do something with bar
        }
};

有关构造函数初始化列表的更多信息此处和此处。

More info on the constructor's initialization list here and here.

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