c# - C#在实例化时递增静态变量

Question

我有一个bankAccount对象，我想使用构造函数来增加。目的是使类实例化的每个新对象都增加它。

注意：我已经重写ToString（）以显示accountType和accountNumber；

这是我的代码：

public class SavingsAccount
{
    private static int accountNumber = 1000;
    private bool active;
    private decimal balance;

    public SavingsAccount(bool active, decimal balance, string accountType)
    {
        accountNumber++;
        this.active = active;
        this.balance = balance;
        this.accountType = accountType;
    }
}

为什么当我将其插入main时像这样：

class Program
{
    static void Main(string[] args)
    {
        SavingsAccount potato = new SavingsAccount(true, 100.0m, "Savings");
        SavingsAccount magician = new SavingsAccount(true, 200.0m, "Savings");
        Console.WriteLine(potato.ToString());
        Console.WriteLine(magician.ToString());
    }
}

我得到的输出不会单独增加它，即

savings 1001
savings 1002

但是我得到了：

savings 1002
savings 1002

我如何使其成为前者而不是后者？

Answer 1

因为在类的所有实例之间共享静态变量。您需要一个静态变量来保留全局计数，而一个非静态变量来保存实例化时的当前计数。将上面的代码更改为：

public class SavingsAccount
{
    private static int accountNumber = 1000;
    private bool active;
    private decimal balance;
    private int myAccountNumber;

    public SavingsAccount(bool active, decimal balance, string accountType)
    {
        myAccountNumber = ++accountNumber;
        this.active = active;
        this.balance = balance;
        this.accountType = accountType;
    }
}

class Program
{
    static void Main(string[] args)
    {
        SavingsAccount potato = new SavingsAccount(true, 100.0m, "Savings");
        SavingsAccount magician = new SavingsAccount(true, 200.0m, "Savings");
        Console.WriteLine(potato.ToString());
        Console.WriteLine(magician.ToString());
    }
}

然后在ToString（）重载中，应打印myAccountNumber而不是静态变量。