c# - 什么时候使用构造函数？

Question

我在网上学习 c#，我刚刚完成了一个练习，我应该创建一个名为“People”的类并创建 5 个可以使人民独一无二的变量：

   public string name;
    public int age;
    public double heigth;
    public double weigth;
    public string nationality;
    public int shoeSize;

我还创建了一个名为“Bank”的类并声明了 4 个成员：

    int accountNumber;
    string firstName;
    string lastName;
    string bankName;

然后，我收到了一个问题：“如果您认为银行类与一个人（People 类）相关联，您将如何在“Bank”类中使用“People”类？

现在我显然不明白什么是精神......有什么想法吗？

编辑：我什么时候需要构造方法？

score 2 · Accepted Answer

它可能很简单：

public class People // I would call it person though, as People is plural
{
    public int age;
    public double heigth;
    public double weigth;
    public string nationality;
    public int shoeSize;
}

public class Bank // I would call it BankAccount though
{
    int accountNumber;
    string firstName;
    string lastName;
    string bankName;

    // The answer to the question:
    People owner; // <-- Here the bank account has a reference to the People class, 
                  // you provided in the constructor

    // And if you need the constructor
    public Bank(People owner, int accountNumber)// <-- This is the constructor
    {
        this.accountNumber = accountNumber;
        this.owner = owner;
    } // <-- The constructor ends here.
}

score 2 · Accepted Answer

这不是构造函数，而是试图告诉您，您可以在您创建的另一个类中将您创建的类作为属性。

在他们的示例中，每家银行都有一个人，因此您可以将People类作为属性调用Person来表示该帐户属于谁。您可以通过将以下内容添加到您的Bank课程中来做到这一点：

public People person { get; set; }

就构造函数而言，如果您想设置一些默认属性，则需要一个。考虑这个构造函数Bank：

public Bank()
{
    accountNumber = 1;
    firstName = "Default";
    lastName = "Default";
    bankName = "Default";
    person = new People();
}

看到创建的最后一行了person吗？如果您删除了它，但随后尝试这样做，this.person.name您将得到一个NullReferenceException. 那是因为默认情况下您person的值为null.

score 0 · Accepted Answer

怎么样

public class Person
{
    //A property for Name

    //A property for Address 
}

在另一个类中，用于收集的属性Persons

public List<Person> People { get; set; }

score 0 · Accepted Answer

这就是我要走的路：

public class Person
{
    public int Age { get; set; } // I would use properties and public properties are 
                                 // starting with a great letter
    public double Heigth { get; set; }
    public double Weigth { get; set; }
    public string Nationality { get; set; }
    public int ShoeSize { get; set; }
}

public class BankAccount
{
    private Person _person; // private field for the person object
    public int AccountNumber { get; private set; } // public propertie for the account 
                                                   // number with a private setter 
                                                   // because normally you want to read
                                                   // that from the outside but not set
                                                   // from the outside
    public string FirstName
    {
        get { return _person.FirstName; }
    }
    public string LastName;
    {
        get { return _person.LastName; }
    }
    public string BankName { get; set; }

    public Bank(Person person, int accountNumber)
    {
        AccountNumber = accountNumber;
        _person = person;
    }
}

请务必记下来自属性、方法等的访问参数。

c# - 什么时候使用构造函数？

4 回答 4

Related

Reference