这是因为,constructor initializer list是直接初始化了数据成员(1步),而如果赋值在constructor body里,就是在进入body前进行了初始化,然后在body中进行赋值(2步),这会涉及到效率问题。 除了效率问题,还有一些情况,我们不得不、必须使用constructor initializer list。在看下去之前,不妨想一想,在什么情况下,只能用...
本文探讨构造函数初始值列表(constructor initializer list)这一C++特性，主要关注其行为、适用场景以及相关细节。构造函数初始值列表用于在构造函数定义时直接初始化数据成员，简化代码并提升效率。构造函数初始值列表的行为遵循三步初始化流程。首先，使用初始值列表中的值进行初始化（通过调用与实参相对应的构造...
: length{len}, height{hgt}is the member initializer list. length{len}initializes the member variablelengthwith the value of the parameterlen height{hgt}initializes the member variableheightwith the value of the parameterhgt. When we create an object of theWallclass, we pass the values for th...
// With Initializer List class MyClass { Type variable; public: MyClass(Type a):variable(a) { // Assume that Type is an already // declared class and it has appropriate // constructors and operators } }; With the Initializer List, following steps are followed by compiler:1...
When foo is instantiated, the members in the initialization list are initialized with the specified initialization values. In this case, the member initializer list initializes m_x to the value of x (which is 6), and m_y to the value of y (which is 7). Then the body of the construc...
In C++, We can have more than one constructor in a class with same name, as long as each has a different list of arguments. Overloaded constructors essentially have the same name (name of the class) and different number of arguments. A constructor is called depending upon the number and ...
Constructorsare non-staticmember functionsdeclared with a special declarator syntax, they are used to initialize objects of their class types. Syntax Constructors are declared using memberfunction declaratorsof the following form: class-name(parameter-list (optional))except (optional)attr ...
Hi I thought classname obj{Val} is initializer list... So, what is classname obj = {Val} Does second option i.e. with equal to call implicit constructor ? #include <iostream> using namespace std; class X { public: int x; explicit X(int x) : x(x){} }; int main() { X a ...
To call a constructor, you use the class name together with parameters surrounded by braces or parentheses. c++ 复制 class Box { public: Box(int width, int length, int height){ m_width = width; m_length = length; m_height = height; } private: int m_width; int m_length; int m_...
class Box { public: // Default constructor Box() {} // Initialize a Box with equal dimensions (i.e. a cube) explicit Box(int i) : m_width(i), m_length(i), m_height(i) // member init list {} // Initialize a Box with custom dimensions Box(int width, int length, int height...