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