C++翁恺学习07-构造和析构

c++是一个注重效率的语言，不会自己做初始化，区别于java，自己搬进来自己打扫;

vs debug模式中未初始化的内存是十六进制的“0xcd，两个构成中文“烫”;

依赖于的程序员的自觉性，素养;

定义了一个对象，对象里面的数据没有初始化。

if a class has a constructor,the compiler(编译器) automatically calls that constructor at the point an object is created,before client programmers can get their hands on the objectthe name of the constructor is the same as the name of class how a constructor does?

class X {
    int i;
public:
    X();
};

1. 构造函数X没有返回类型,和类名一模一样；

2. 对象被创造的时候 X() 被自动调用;

3. X() 也是类的成员函数，this指的是那个对象的地址；

X a;----->a.X()

the constructor can have arguments to allow you to specify how an object is created,give it initialization values,and so on

Tree(int i){...} // 带参数构造函数
Tree t(12);  // 12传给构造函数

in C++,cleanup is as important as initialization and is there guaranteed with destructor

the destructor is named after the name of the class with a leading tilde （~）.the destructor never has any arguments

class Y{
public:
    ~Y();  // 波浪号
};

没有参数，没有返回类型；被析构之前，析构函数被调用，空间被收回。

the destructor is automatically by the compiler when the object goes out of scopethe only evidence for a destructor call is the closing brace of the scope that surrounds the object