C# 检查属性的属性是否为 null 的优雅方法

检查属性的属性是否为 null 是在编程中常遇到的问题之一。在 C# 中，我们可以使用一些优雅的方法来检查属性的属性是否为 null。本文将介绍一种常用的方法，并提供相应的案例代码。

public class Address
{
    public string Street { get; set; }
}
public class Person
{
    public Address Address { get; set; }
}
public class Program
{
    public static void Main()
    {
        Person person = new Person();
        string street = person?.Address?.Street;
        
        if (street == null)
        {
            Console.WriteLine("Street is null.");
        }
        else
        {
            Console.WriteLine("Street is not null.");
        }
    }
}

public class Address
{
    public string Street { get; set; }
}
public class Person
{
    public Address Address { get; set; }
}
public class Program
{
    public static void Main()
    {
        Person person = new Person();
        string street = person?.Address?.Street ?? "Unknown";
        
        Console.WriteLine("Street: " + street);
    }
}