Question

我在C＃中编程时遇到此错误： 'BankSystem.Account'不包含带0参数的构造函数

我的课程是：

首先，帐户类：

 public abstract class Account : IAccount
{

    private static decimal minIncome = 0;
    private static int minAge = 18;

    private string name;
    private string address;
    private decimal age;
    private decimal balance;

    public Account(string inName, decimal inAge, decimal inBalance, string inAddress)
    {
        if (AccountAllowed(inBalance, inAge))
        {
            name = inName;
            address = inAddress;
            balance = inBalance;
            age = inAge;

            Console.WriteLine("We created the account. \nName is " + name + " \nThe address is: "
            + address + "\nThe balance is " + balance);

        }
        else
        {
            Console.WriteLine("We cann't create the account. Please check the balance and age!");
        }
    }

    //public CustomerAccount(string newName, decimal initialBalance)

    public Account(string inName, decimal initialBalance)
    {
    }

其次，CustomerAccount类：

 public class CustomerAccount : Account
{
    private decimal balance = 0;
    private string name;

    public CustomerAccount(string newName, decimal initialBalance)
    {
        name = newName;
        balance = initialBalance;
    }

    public CustomerAccount(string inName, decimal inAge, decimal inBalance, string inAddress)
        : base(inName, inAge)
    {

        // name = inName;
        //age = inAge;
    }

    public CustomerAccount(string inName, decimal inAge)
        : base(inName, inAge)
    {

        // name = inName;
        //age = inAge;
    } ......

Answer 1

因为您已在类中定义了带参数的构造函数，所以默认情况下不会获得默认构造函数。

您的帐户类已定义构造函数：

public Account(string inName, decimal inAge, decimal inBalance, string inAddress)
public Account(string inName, decimal initialBalance)

你可以定义一个默认构造函数，如。

public Account() 
{
}

您得到的错误是因为，CustomerAccount的下面的构造函数隐式调用Account基类的默认构造函数，因为您没有指定任何其他基本构造函数，例如:base(arg1,arg2);

 public CustomerAccount(string newName, decimal initialBalance)
    {
        name = newName;
        balance = initialBalance;
    }

以上内容与：

相同

 public CustomerAccount(string newName, decimal initialBalance) : base()

Answer 2

你也需要在这里“链接”到基础构造函数：

public CustomerAccount(string newName, decimal initialBalance)
    : base(newName, 0)    // something like this
{
    name = newName;
    balance = initialBalance;
}

Answer 3

简单。您的Account类不包含具有零参数的构造函数，例如

public Account()
{

}

答案在错误消息中。

在正确的参数中创建Account类传递的新实例时，例如

Account account = new Account("John Smith", 20.00);

或者创建一个零参数的构造函数。

Answer 4

您正在初始化Account这样的课程

new Account();

但应该

new Account("name", ...);

根据你的构造函数定义。

没有在C＃中带0个参数的构造函数

4 个答案: