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。
Default constructor is also known as zero argument or no argument constructors. It is used to initialize data members of class. It does not have any argument. Note that - If we do not create constructor in user defined class. Then compiler automatically inserts a constructor with empty body ...
Example of Default Constructor or Zero Argument Constructor #include <iostream>usingnamespacestd;classDemo{private:intA;intB;intC;public:Demo();voidset(intA,intB,intC);voidprint(); }; Demo::Demo() { A=1; B=1; C=1; }voidDemo::set(intA,intB,intC) {this->A=A;this->B=B;this->...
1. Default Constructor A default constructor is parameterless. If a class doesn't have a constructor then a default constructor gets called when object is created. The default constructor is added to a class by default if you don't add any constructor to your class. The default constructor sh...
(02/15/2007新增)default constructor在C++重要的原因,在於對built-in type作初始化的動作,如int為0,double為0.0...,這些東西算是繼承自C語言的『歷史共業』,在C#/Java這些較新的語言中,default constructor的重要性就沒那麼大。 雖然有synthesized default constructor這個東西,但建議無論什麼時候,還是該寫自己的...
Note: Even if we do not define any constructor explicitly, the compiler will automatically provide a default constructor implicitly. The default value of variables is 0 in case of automatic initialization. 2.Parameterized Constructors: It is possible to pass arguments to constructors. Typically, the...
Master C++ constructors with this comprehensive guide for beginners. Learn to initialize objects, set default values, and perform complex initialization tasks.
Compiler-Generated Default Constructor The first SpreadsheetCell class definition in this chapter looked as follows: classSpreadsheetCell {public:voidsetValue(doubleinValue);doublegetValue()const;protected:doublemValue; }; This definition does not declare a default constructor, but still, the code that...
}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. ...
declare a static constructor, which initializes static members of the type. Static constructors are parameterless. If you don't provide a static constructor to initialize static fields, the C# compiler initializes static fields to their default value as listed in theDefault values of C# types...