class Foo1中,15行和16行使用了兩個constructor,但class Foo2中,26中只使用了一個constructor就完成了,關鍵就在使用了default argument,這種寫法使程式更加精簡。
In C++, you can provide the default values /arguments to the data members by using the default arguments while defining the constructor of the class.
0 - This is a modal window. No compatible source was found for this media. If your class has const members, then default arguments can be provided in the constructor to make initialization easier. Syntax This constructor uses default arguments (length = 5 and width = 10) to initialize the...
In the function definitions, if we declare default argument for one variable, then all the variables after that need to have default arguments. Like below is not a valid function definition using default arguments and will throw compilation error, int func(int a, int b=0, int c) //This...
#include <iostream> using namespace std; class MyClass { public: int a, b; // Default constructor (no arguments) MyClass() : a(0), b(0) { cout << "Default constructor called" << endl; } // Overloaded constructor with one argument MyClass(int x) : a(x), b(0) { cout <<...
class X { public: X(); // Default constructor with no arguments X(int = 0); // Default constructor with one default argument X(int, int , int = 0); // Constructor }; Note: You can declare default constructors as explicitly defaulted functions or deleted functions. For more information...
arg);// non-default constructor};voidC::f(inti=3){}// error: default argument already// specified in class scopevoidC::g(inti=88,intj){}// OK: in this translation unit,// C::g can be called with no argumentC::C(intarg=1){}// Error: turns this into a default constructor...
A constructor without any arguments or with default values for every argument, is treated as default constructor. It will be called by the compiler when in need (precisely code will be generated for default constructor based on need).
If we call the function without an argument, it uses the default value ("Norway"): Example voidmyFunction(string country ="Norway") { cout<< country <<"\n"; } intmain() { myFunction("Sweden"); myFunction("India"); myFunction(); ...
Reflect.construct(target, argument, new_target)函数以target为构造函数创建对象,这里new_target提供原型,然后行为跟new func()类似。 上面的知识都比较简单,所以也不想细说了,如果读者不是很清楚的话,请自行查阅下相关资料吧,这里主要关注JS...