Question

我是C＃的新学员，而且我上课时遇到了困难。特别是在尝试使用对象时。我一直试图制作一个计算器，并因错误而被迫缩短。我试图自己解决这个问题，但在尝试修复之后我似乎更加困惑。

我试图创建一个用户输入两个数字的应用程序，它使用一个类对象来计算它们并将它带回main方法。如果经常被问到，请道歉。并提前谢谢你。

class Program
{
    static void Main(string[] args)
    {    

    Console.WriteLine("Please enter a number");
        int num1; 
       //ask user for number
        num1 = int.Parse(Console.ReadLine());
        Console.WriteLine("Please enter a second number");
        int num2;


        //ask user for number
        num2 = int.Parse(Console.ReadLine());

        //initialize class object
        Addition addi = new Addition();

        Console.WriteLine("The answer of both {0} and {1} is {2}", num1, num2, addi);

        Console.ReadLine();
    }
}

这是将进行添加并将其传递给main方法的类。

class Addition
{
   public static void Add(int x, int y)
    {
        x;
        y;
        int ans;
        ans = x + y;
        //get an error "Since 'Addition.add' returns void, a return keyword must not be followed by an object expression "
        return ans;
    }


}

Answer 1

这个类有两种工作方式......静态或实例化。

实例化

如果你想让main方法以这种方式工作......

Addition addi = new Addition();
Console.WriteLine("The answer of both {0} and {1} is {2}", num1, num2, addi);

然后你的Addition类应该更像这样：

class Addition
(
    private readonly int result;

    public Addition(int num1, int num2)
    {
        result = num1 + num2;
    }

    public override string ToString()
    {
        return result.ToString();
    }
}

然后它会稍作改动：

Addition addi = new Addition(num1, num2);  //Have to pass the values in
Console.WriteLine("The answer of both {0} and {1} is {2}", num1, num2, addi);

静态

静态方法不需要实例，因此您必须更改此内容：

Addition addi = new Addition();  
Console.WriteLine("The answer of both {0} and {1} is {2}", num1, num2, addi);

对此：

var addi = Addition.Add(num1, num2);
Console.WriteLine("The answer of both {0} and {1} is {2}", num1, num2, addi);

你的班级应该是这样的：

static class Addition
{
    static public int Add(int num1, int num2)
    {
        return num1 + num2;
    }
}

“方法必须具有返回类型”和＆＃34;返回关键字后面不能跟对象表达式＆＃34;错误

1 个答案:

实例化

静态