首先澄清一個概念,default constructor定意為沒有參數的constructor,並非compiler自動產生的constructor,compiler自動產生的叫做synthesized default constructor(C++ Primer 4th P.458)。 當我們的class中沒有任何constructor時,compiler會自動幫我們產生synthesized defualt constructor。如以下範例 1 #include<iostream> 2 #incl...
D():b(int){a.A::A();b.B::B(int);c.C::C();// 其他} 注意顺序是按照声明顺序来的。 2 "带有Default Constructor"的Base Class 类似道理,如果没有任何constructors的class继承自一个带有Defaultor Constructor的Base class, 那么derived class的default constructorh会被合成出来,调用Base class的default...
};intintVal; };classBar{public: Foo foo; Sample sample; std::string str;intintVal; };voidinit(){ Bar bar;printf("bar.foo.intVal: %d\n",bar.foo.intVal);printf("bar.sample.intVal: %d\n",bar.sample.intVal);printf("bar.str: %s\n", bar.str.c_str());printf("bar.intVal: %d \...
生成的default constructor里会调用成员的default constructor;如果是自己定义了default constructor,compiler也...
classD:publicC{private:intnum;public:intNum()const{returnnum;}voidNum(intval){num=val;}virtual...
In my reading, this leaves open the possibility that I declare a constructor but the compiler may or may not declare a default constructor. classFoo{public:// Foo();(i ); }
Every direct base ofThas a trivial default constructor. Every non-static member of class type (or array thereof) has a trivial default constructor. A trivial default constructor is a constructor that performs no action. All data types compatible with the C language (POD types) are trivially def...
Constructor default-public and private variables 我知道java并且我现在学习c。我比其他语言更容易学习它有很多相同的东西。我的问题是在一本书的类上有一个完整的构造函数,但我没有在任何地方面对默认构造函数.有 c 默认构造函数,如果是,我应该写吗?另外,我想测试一些东西,在这个类上有 public: 和它的下面有变...
The classes of all the nonstatic data members ofAhave trivial constructors If any of the above are false, then the constructor isnontrivial. A union member cannot be of a class type that has a nontrivial constructor. Like all functions, a constructor can have default arguments. They are ...
class Bar { public: Foo foo; char *str; }; void foo_bar() { Bar bar; // Bar::foo must be initialized here if ( str ) { } ... } The synthesized default constructor contains the code necessary to invoke the class Foo default constructor on the member object Bar::foo, but it do...