Question

我正在通过一些编码练习来教自己C＃，现在已经困了几天，试图计算其他行星的不同时间段，该是时候寻求帮助了。我至少已经摆脱了错误，并且开始返回一些东西，但是现在我一生都无法弄清楚为什么seconds不会以一种稳定的方式存储然后调用方法。它只是返回零。请参见下面的代码。

    public class SpaceAge
    {
        public long seconds;

        public SpaceAge(long seconds)
        {
            Console.WriteLine("Space Age in Seconds:" + seconds); 
        }

        public double OnEarth()
        {
            double result = seconds / 31557600;
            return result;
        }
        public double OnMercury()
        {
            double result = seconds * 0.2408467;
            return result;
        }
    }  

    class Program
    {
        public static void Main()
        {
             Console.WriteLine("**Main Function Executing**");
             var age = new SpaceAge(10000000000);
             Console.WriteLine("Earth years:" + age.OnEarth());
             Console.WriteLine("Mercury years:" + age.OnMercury());       
        }
    }

它返回：

BBs-iMac:space-age bb$ dotnet run
**Main function executing**
Space Age in Seconds:10000000000
Earth years:0
Mercury years:0

Answer 1

您没有初始化字段。另外，由于seconds是long，因此应在除数上使用后缀D。

using System;

public class SpaceAge
{
    public long seconds;
    public SpaceAge(long seconds)
    {
        this.seconds = seconds; // missing
        Console.WriteLine("Space Age in Seconds:" + seconds);
    }

    public double OnEarth()
    {
        double result = seconds / 31557600D; // add an 'D'
        return result;
    }

    public double OnMercury()
    {
        double result = seconds * 0.2408467D; // add an 'D'
        return result;
    }
}

public class Program
{
    public static void Main()
    {
        Console.WriteLine("**Main Function Executing**");
        var age = new SpaceAge(10000000000);
        Console.WriteLine("Earth years:" + age.OnEarth());
        Console.WriteLine("Mercury years:" + age.OnMercury());
    }
}

输出：

没有'D'后缀

**Main Function Executing**
Space Age in Seconds:10000000000
Earth years:316
Mercury years:2408467000

后缀'D'：

**Main Function Executing**
Space Age in Seconds:10000000000
Earth years:316.88087814029
Mercury years:2408466935.15778

Answer 2

构造函数有两个不同的名为seconds的变量：类成员和参数。您需要这样做：

public SpaceAge(long seconds)
{
    this.seconds = seconds;
    Console.WriteLine("Space Age in Seconds:" + seconds); 
}

此外，OnEarth()中的算术完全发生在整数空间中，这意味着结果的任何小数部分都会被截断。您需要确保除法运算的至少一侧是浮点类型：

public class SpaceAge
{
    public long seconds;

    public SpaceAge(long seconds)
    {
        this.seconds = seconds;
        Console.WriteLine("Space Age in Seconds:" + seconds); 
    }

    public double OnEarth()
    {
        //the "D" at the end of the number means it is a double, not an int.
        return seconds / 31557600D;
    }
    public double OnMercury()
    {
        return seconds * 0.2408467D;
    }
}

类方法不使用类变量

2 个答案: