关于CPP类中字符串成员初始化

直接看代码吧

#include 
#include 
 
/*
A string is actually an object of the C++ Standard Library class string. 
This class is defined in header , and the name string, like cout, belongs to namespace std.
To enable string-relative-statement compile, includes the  header.
The using directive in "using namespace std;" allows us to simply write string rather than std::string.
For now, you can think of string variables like variables of other types such as int.
The class template basic_string provides typical string-manipulation operations such as
copying, searching, etc.
The template definition and all support facilities are defined in namespace std; 
these include the typedef statement "typedef basic_string< char > string;"that creates the alias type string
for basic_string. To use strings, include header .
*/
 
using std::cout;
using std::cin;
using std::endl;
using std::string;
 
 
/*----------------------------------------------------*/
 
class Cat
{
    private:
        std::string _name = "Mogo";
        int _age = 20;
 
    public:
 
    Cat(string name)
    {
        if(name.length() < 5)
            _name = "hehda dsa  You!";
        else
             _name = name;
    }
 
 
    //使用初始化列表通常是首选方法
    //因为它更高效，并且可以避免在构造函数体内对std::string等类型进行复制操作时产生的额外开销。 
    Cat():_name("DanDan")
    {
        _age = 100;
    }
 
    Cat(int age):_name(4, 'Y'), _age(age) {}
 
    string shout(void)
    {
        return "my name is " + _name + " \"MI\"";
    }
 
    void show(void)
    {
        cout << "Age is: " << std::hex << _age << endl;
    }
};
 
 
/*----------------------------------------------------*/
 
int main()
{
    std::cout<<"Hello, World!"<
 
    Cat cat = Cat("Ista");
    Cat l_cat = Cat();
    Cat h_cat = Cat(255);
 
    cout << cat.shout() << endl;
    cout << l_cat.shout() << endl;
    cout << h_cat.shout() << endl;
 
    cat.show();
    l_cat.show();
    h_cat.show();
 
    string pre_firm("borgward");
    string rep_pos(8, 'X');
 
    cout << pre_firm << "---" << rep_pos << endl;
 
    return 0;
}
 
/*----------------------------------------------------*/

运行结果：

参考文章：

C++类成员的初始化_c++ 类成员初始化-CSDN博客

（完）