C++基础之初始化列表

    Initializer list

#include <iostream> using namespace std; class Point { private: const float x, y; Point(float xa = 0.0, float ya = 0.0) :y(ya), x(xa) {} };

    ◆ Can initialize any type of data

        — pseudo-constructor calls for built-ins

        — No need to perform assignment within body of constructor

    ◆ Order of initialization is order of declaration

        — Not the order in the list!

        — Destroyed in the reverse order.

    Initialization vs. assignment

Student::Student(string s): name(s) {}

    initialization

    before constructor

Student::Student(string s) {name = s;}

    assignment

    inside constructor

    string must have a default constructor

【例】

#include <iostream> using namespace std; class A { public: A(int i) {} }; class B { public: A a; B() { a = 0; } };

    以上代码会报错：类 "A" 不存在默认构造函数。上例的错误揭示我们在初始化类的对象时，建议使用初始化列表，而不是在构造函数中进行赋值