需要一些 C# 的重载信息

Question

我遇到以下问题，想看看是否有人可以帮助我。详细信息在代码中，但我试图重载构造函数并且参数名称给了我一个错误：

using system
    //blah, blah blah

        class Animal
        {
            private string name;
            private string race;
            private double _weight;
            private double _age;


        public Animal(string n,string r, double a, double w)
        {
            name = n;
            race = r;
            age = a;
            weight = w;
        }

            public double age
            {
                get
                {
                    return _age;
                }
                set
                {
                    if (value > 0 && value <= 25)
                    {
                        _age = value;
                    }
                    else
                    {
                        do
                        {
                            Console.WriteLine("Invalid Age!\nDog's age: " + value);
                            Console.Write("Please enter dog's age: ");
                            age = double.Parse(Console.ReadLine());

                        } while (_age < 0 && age > 25);
                    }
                }
            }
            public double weight
            {

                get
                {
                    return _weight;
                }
                set
                {
                    if (value > 0 && value <= 60)
                    {
                        _weight = value;
                    }
                    else
                    {
                        do
                        {
                            Console.WriteLine("Invalid Weight!\nDog's weight: " + value);
                            Console.Write("Please enter dog's weight: ");
                            weight = double.Parse(Console.ReadLine());
                        } while (_weight < 0 && _weight >= 60);
                    }
                }
            }

            public Animal()
            {
                Console.WriteLine("Invalid Age!" + "\nInvalid Weight!");
                Console.Write("\nInformation for the 1st dog : ");
                getdetails();

            }
            public void info()
            {
                Console.Write("\nInformation for the 2nd dog: ");
                Console.WriteLine("\nName: " + name + ", Race: " + race
                    + ", Age: " + age + ", Weight: " + weight);

                Console.ReadLine();
            }
            public void getdetails()
            {
                _age = 1;
                _weight = 1;
                Console.WriteLine("\nName: No Name, Race: No Race" + ", Age: " + _age + ", Weight: "
                    + _weight);
                Console.WriteLine();
            }





            public static void Main(String[] args)
            {
                Animal dog = new Animal();
                Animal dog2 = new Animal(name,race,age,weight);***//HERE'S THE ERROR!
//SO HERE ARE WHERE MY TROUBLES LIE. I CREATED A NEW OBJECT AND I AM TRYING TO PASS
THE ENTERED INFORMATION FROM THE USER TO ONE OF MY CONSTRUCTORS BUT 
IM HAVING A TOUGH TIME DOING IT. COULD SOMEBODY HELP PLEASE?***

                Console.Write("Please enter your dog's name: ");
                dog.name = Console.ReadLine();
                Console.Write("Please enter your dog's race: ");
                dog.race = Console.ReadLine();
                Console.Write("Please enter your dog's age: ");
                dog.age = double.Parse(Console.ReadLine());
                Console.Write("Please enter your dog's weight: ");
                dog.weight = double.Parse(Console.ReadLine());

                dog.info(); 


            }
        }
    }

现在我知道有很多东西不必写在这段代码中，但这就是我应该这样做的方式，我只是在参数方面遇到问题，请帮忙？

Answer 1

您似乎混淆了构造函数调用和函数调用-> animal(name, race ...) 只是代码中的一个函数，因此您不能直接调用它。看看如何重载构造函数。顺便说一句，很高兴知道您使用的是哪种语言^^

抱歉，我正在用我的 C++ 帽子分析您的代码……而在 C# 中，除了将正确的值作为参数传递之外，您所做的一切都非常正确。您试图在定义/分配它们之前传递值，这就是您收到错误的原因。 所以对于 dog2 你可能想要这样做。

   public static void Main(String[] args)
            {
                //variable declation
                string name, race;
                double age, weight;

                //variable assigned user inputs
                Console.Write("Please enter your dog's name: ");
                name = Console.ReadLine();
                Console.Write("Please enter your dog's race: ");
                race = Console.ReadLine();
                Console.Write("Please enter your dog's age: ");
                age = double.Parse(Console.ReadLine());
                Console.Write("Please enter your dog's weight: ");
                weight = double.Parse(Console.ReadLine());

                // call of the overloaded constructor with the right parameters
                Animal dog2 = new Animal(name,race,age,weight);

                dog2.info(); 


            } 

希望对你有帮助，祝你好运:)

Answer 2

您的示例有两个Constructors，一个默认无参数Constructor、Animal() 和一个需要四个 参数Animal(string n, string r, double a, double w) 的Constructor。 Constructor 的签名会告知您预期的 parameter(s) 的数量和 type。

Animal dog = new Animal();

由于您使用的是默认的无参数构造函数，因此上述操作毫无疑问。

Animal dog2 = new Animal(name, race, age, weight);

当您尝试使用参数化构造函数时，上述内容不起作用，但是，您正在以unresolved symbols 的形式传递它。

您需要做的是声明（并在需要时实例化）一些将传递给构造函数的变量：

public static void Main(string[] args)
{
    string name = "SomeName";
    string race = "SomeRace";
    double age = 12;
    double weight = 9001;

    Animal dog2 = new Animal(name, race, age, weight);
}

如果您需要/希望您的用户定义传递给参数化构造函数的参数值，那么您将需要执行类似于在示例中进一步收集用户输入的方式（使用 Console.ReadLine()）。

*编辑：*

@ “你到底是什么意思，因为我确实声明了字符串和双变量来传递它们，但它没有用。”

您的那部分代码似乎已被省略或遗漏。

@ “你说我必须在动物类的构造函数中要求用户输入？还是创建一个接受输入的方法来更改传递的变量的值？。 "

您正在尝试使用Main 函数内的参数化构造函数创建Animal 的实例，因此您需要在创建之前声明并实例化将用作Animal 构造函数参数的变量构造函数调用和Main 函数内部。

@ “就像我说的那样，我确实声明了字符串和双精度，但我没有为它们赋值，因为就像你说的那样，我试图让用户定义我的参数，但我是不知道该怎么做。”

您的代码已经有一个如何获取用户输入并将其分配给变量的示例：

// You wrote this [:
Console.Write("Please enter your dog's name: ");
dog.name = Console.ReadLine();
Console.Write("Please enter your dog's race: ");
dog.race = Console.ReadLine();
Console.Write("Please enter your dog's age: ");
dog.age = double.Parse(Console.ReadLine());
Console.Write("Please enter your dog's weight: ");
dog.weight = double.Parse(Console.ReadLine());

上面使用Console.ReadLine()请求用户输入，然后将用户输入的值分配给关联的Animalproperty。比如：

dog.name = Console.ReadLine();

以上假设已经有一个名为dog 的Animal 的有效实例。 dog 有多个公共properties (name, race, age 和weight). The left side (leftoperand) of theassignment operator(=) is the object property that you want to assign a value to. The right side (rightoperand@535454543543543543543543 @Console.ReadLine()(as in this example), a mathematical calculation or a hard coded value etc. However theright operandis derived, it isassignedto theleft operand`。这是你的任务。

另一个例子：

private static void Main(string[] args)
{
    // Obtain parameter values from user

    Console.WriteLine("Enter a name");
    string name = Console.ReadLine();
    Console.WriteLine("Enter a race");
    string race = Console.ReadLine();
    Console.WriteLine("Enter an age");

    // Console.ReadLine() reads values in as strings
    // Therefore you will need to convert the values you want as doubles
    double age;
    while (!double.TryParse(Console.ReadLine(), out age))
    {
        Console.WriteLine("The value you entered is not a valid age, please enter a valid age");
    }
    Console.WriteLine("Enter a weight");
    double weight;
    while (!double.TryParse(Console.ReadLine(), out weight))
    {
        Console.WriteLine("The value you entered is not a valid weight, please enter a valid weight");
    }

    // Create an instance of Animal
    Animal dog2 = new Animal(name, race, age, weight);
}