C#返回值,但不断收到错误.为什么？

Question

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我是Java,Obj-C的C#语言转换的新手.它看起来和Java非常相似,但我在很简单的事情上遇到麻烦.我创建了两个单独的类文件,Class-A和Class-Human.

A级规范

它包含声明的静态main方法.我尝试创建Class-Human的新实例.

public static void main(String args[])
{
      Human human = new Human("Yoon Lee", 99);
      int expected = human.getNetID; //<-gets the error at this moment.
}

人类规范

namespace Class-A
{
    public class Human
    {
        public String name;
        public int netId;

        public Human(String name, int netId)
        {
            this.name = name;
            this.netId = netId;
        }
     public int getNetID()
     {
         return netId;
     }
}     

为什么不能复制到局部变量？编译器提示我错误

'Cannot convert method group of 'getNetID' delegate blah blah'

谢谢.

Answer 1

将方法调用更改为:

int expected = human.getNetID();

在C#中,方法调用需要()包含以逗号分隔的参数列表的parantheses.在这种情况下,该getNetID方法是无参数的; 但是空的parantheses仍然需要表明你的意图是调用方法(而不是,例如,将method-group转换为delegate-type).

此外,正如其他人所指出的那样,方法的返回类型与您分配其值的变量之间存在不匹配,您将不得不以某种方式解决该变量(更改字段类型和方法) return-type to int/ parse the string as an integer,etc.).

另一方面,C#本身支持getter-setter语义的属性,因此写这个的惯用方法如下:

//hyphens are not valid in identifiers
namespace ClassA
{
    public class Human
    {
        // these properties are publicly gettable but can only be set privately
        public string Name { get; private set; } 
        public int NetId { get; private set; }

        public Human(string name, int netId)
        {
            this.Name = name;
            this.NetId = netId;
        }

        // unlike Java, the entry-point Main method begins with a capital 'M'
        public static void Main(string[] args)
        {
            Human human = new Human("Yoon Lee", 99);
            int expected = human.NetId; // parantheses not required for property-getter
        }

    }
}