1structtest{2inta;3};4intmain(){5structtest t;6printf("%d\n",t.a);7} 若test的默认构造函数产生,并导致a被初始化为0,那么C++中就将输出0。但C中没有构造函数这一概念,所以就将输出任意值。早期C++是目地之一为了很好的兼容C代码,所以C++编译器为了更好的兼容C,就选择了这种看似很不可思议的方法。
Learn: What is default constructor in C#? How it is declared and defined, what default constructor does? Default constructor is also known as zero argument or no argument constructors. It is used to initialize data members of class.
class ClassName { public: // Default constructor ClassName() { // Initialization or setup code } }; Here is the following example for the Default constructor.ExplanationIn this example, first, we created the class named DemoDC. In class, two private member variables num1 and num2 of type ...
}int main(){construct c;cout << "a: " << c.a << endl<< "b: " << c.b;return 1;} Translate 0 Kudos Reply All forum topics Previous topic Next topic 0 Replies Community support is provided Monday to Friday. Other contact methods are available here. ...
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Like all functions, a constructor can have default arguments. They are used to initialize member objects. If default values are supplied, the trailing arguments can be omitted in the expression list of the constructor. Note that if a constructor has any arguments that do not have default values...
default constructorstructG{G(constG&){}// G::G() is implicitly defined as deleted};structH{H(constH&)=delete;// H::H() is implicitly defined as deleted};structI{I(constI&)=default;// I::I() is implicitly defined as deleted};intmain(){A a;B b;C c;// D d; // compile...
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...
Description : Common mistake of Default Constructor 7 Release : 01/14/2007 1.0 8 */ 9 #include<iostream> 10 11 usingnamespacestd; 12 13 classFoo { 14 public: 15 Foo(intx=0) : x(x) {}; 16 17 public: 18 intgetX() {returnthis->x; } ...
26行的寫法是常犯的錯,Compiler會認為foo為一function,回傳Foo型別object,這算是C++蠻tricky的地方,所以正確的寫法是27行,不加上(),或28行寫法也可以,先利用Default Constructor建立一個temporary object,再使用Copy Constructor將object copy給foo,不過這是使用Copy-initialization的方式,和27行使用Direct-...