c# - 以下代码的输出 : Why would it return rainyday[1] = Sunday and not friday?

Question

为什么它会返回 rainyday[1] = Sunday 而不是星期五？并在其他地方返回 main() 中定义的所有值

  Namespace ConsoleApp_toTestYourself
    {
        public struct forecast
        {
            public int temp { get; set; }
            public int press { get; set; }
        }


        class structStaticTest
        {
            public static void cts(string weather) { weather = "sunny"; }
            public static void cta(string[] rainyDays) { rainyDays[1] = "Sunday"; }
            public static void ctsr(forecast f) { f.temp = 35; }

            static void Main(string[] args)
            {
                string weather = "rainy";
                cts(weather);   //calling static method
                Console.WriteLine("the weather is " + weather);

                string[] rainyDays=new[]{"monday","friday"};
                    cta(rainyDays);  calling static method
                Console.WriteLine("the rain days were on "+rainyDays[0]+"  and   "+ rainyDays[1]);

                forecast f = new forecast { press = 700, temp = 20 };
                ctsr(f);  //calling static method
                Console.WriteLine("the temperature is  " + f.temp + "degree celcius");
                Console.ReadLine();
            }
        }
    }

它的输出是:雨天星期一星期天20摄氏度

Answer 1

因为 cta 方法将 rainyDays[1] 设置为星期日:

public static void cta(string[] rainyDays) { rainyDays[1] = "Sunday"; }

它在写入控制台之前被调用:

cta(rainyDays);  //calling static method
Console.WriteLine("the rain days were on "+rainyDays[0]+"  and   "+ rainyDays[1]);

编辑:关于静态方法之间的差异。其他方法不会更改传递的对象。

首先，cts 不会改变字符串对象:

weather = "sunny";

不会改变原始对象。它创建新的字符串对象 "sunny" 并将其分配给一个变量(方法参数)。

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其次，ctsr 接受结构 forecast 作为参数。结构按值传递，方法接收原始结构的副本并对其进行操作。因此，您的更改不会对 main 方法中的 weather 产生任何影响。

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