zergon321's questions

有 2 个数据集 - 宠物：

Pet[] pets =
        {
            new Pet() { Name = "Vasya", Type = "Cat", Owner = "John" },
            new Pet() { Name = "Borya", Type = "Dog", Owner = "Dean" },
            new Pet() { Name = "Kim", Type = "Hedgehog", Owner = "Mary" },
            new Pet() { Name = "Joka", Type = "Dog", Owner = "John" },
            new Pet() { Name = "Mursick", Type = "Cat", Owner = "Dean" },
            new Pet() { Name = "Mick", Type = "Cat", Owner = "Mary" },
            new Pet() { Name = "John", Type = "Hedgehog", Owner = "John" },
            new Pet() { Name = "Jynx", Type = "Dog", Owner = "Dean" }
        };

和他们的主人：

Owner[] owners =
        {
            new Owner() { Name = "John", Country = "USA" },
            new Owner() { Name = "Mary", Country = "Switzerland" },
            new Owner() { Name = "Dean", Country = "Great Britain" }
        };

从这两组中，我想确定每个国家有多少每种类型的宠物。那些。我需要一个与此SQL查询等效的LINQ查询：

SELECT O.Country, P.Type, Count(P.Type) AS Amount
FROM owners AS O INNER JOIN pets AS P
ON O.Name = P.Owner
GROUP BY O.Country, P.Type;

有可能用LINQ得到这个吗？

有以下 C# 代码：

using System;
using System.Threading.Tasks;
using AlgorithmTools;

namespace AsyncMethods
{
    class Program
    {
        public static async void MethAsync(int num) => Console.WriteLine($"Factorial of {num} is {await FactorialAsync(num)}");

    private static Task<int> FactorialAsync(int num)
    {
        return Task.Factory.StartNew(() =>
                {
                    int result = 1;

                    foreach (int i in new Range(2, num + 1))
                        result *= i;

                    return result;
                });
    }

    static void Main(string[] args)
    {
        MethAsync(5);
    }
}
}

因为 当在返回值块上MethAsync调用并将控制权转移给方法时，程序应该终止而不打印阶乘值，但是，它被打印了。但是，如果不是返回值is ，那么一切都会按原样完成，它将在计算阶乘之前结束。为什么会这样？awaitFactorialAsyncMainvoidMethAsyncTaskMain

Tor客户端通过一系列服务器发送加密流量，而流量本身则使用所有服务器的公钥加密。问题：客户端如何找到链中第一台服务器的IP地址？他甚至从哪里获得有关哪些服务器可用于构建链的信息？他从哪里获得他们的公钥：参考服务器本身，或者从同一个地方，他从哪里获得可用服务器的IP地址？而且，也许，最重要的事情是：如何在确保所有这些程序的同时保持匿名性（在沿着链发送流量本身之前）？

我用DataGridView. 我查看了许多用例，但是当我尝试在自己的代码中做某事时，在调试时，组件本身DataGridView显示为一个灰色矩形，没有任何列和行。该组件仅将程序的主窗体视为数据源Form1。需要在属性列表中编辑哪些内容并添加到代码中才能输入元素并对其进行计数？

在输入数组及其进一步处理（arrayGrid-object DataGridView）的示例中：

private void button1_Click(object sender, EventArgs e)
    {
        arrayGrid.RowCount = 1;
        arrayGrid.ColumnCount = SIZE;

        arrayGrid.Rows.Add();
        for (int i = 0; i < SIZE; i++)
            arrayGrid.Columns.Add("column" + i.ToString(), i.ToString());

        for (int i = 0; i < SIZE; i++)
            arr[i] = int.Parse((string)arrayGrid.Rows[0].Cells[i].Value);

        int min = arr[0];

        for (int i = 1; i < SIZE; i++)
            if (arr[i] < min)
                min = arr[i];

        label3.Text = min.ToString();
    }

Visual Studio 2017看不到头文件Windows.h, WinSock2.h, WS2tcpip.h.
需要安装哪些版本的Visual C++以及需要在 Visual Studio 本身中完成哪些操作才能使用上述所有功能？

为什么在编译时：

using System;

public class Test
{
  public static void Main()
  {
    Lol l = new Lol();
    Console.WriteLine(((IParent)l).Family);
    Console.WriteLine(((IChild)l).Family);
    Console.WriteLine(l.Name);
  }
}

public interface IParent
{
  string Family { get; }
}

public interface IChild : IParent
{
  string Name { get; }
}

public class Lol : IChild
{
  string IParent.Family { get { return "suck"; } }
  string IChild.Family { get { return "duck"; } }
  public string Name { get { return "ross"; } }
}

IdeOne 给出了这个：

prog.cs(27,26)：错误 CS0550：Lol.IChild.Family.get是在接口成员编译失败中找不到的访问器IChild.Family ：1 个错误，0 个警告

有没有可能这样做：web文档一传到用户电脑上，就启动一个js脚本，偷偷下载一个二进制文件到用户电脑上启动执行？如何实施？我自己没学过JS，我主要是想看看自己需要的东西能不能实现。

我正在制作一个简单的 GUI 程序：

彼此相邻的 Entry 和 Button 对象必须低三个单元格。怎么做？这是代码本身：

from tkinter import *

class Shell(Frame):

def __init__(self, window):
    super().__init__(window)
    self.grid()
    self.__clicked = 0
    self.__init_widgets()

def __init_widgets(self):
    self.__lbl = Label(self, text = "Button clicked: " + str(self.__clicked))
    self.__lbl.grid(row = 0, column = 0, columnspan = 2, sticky = W)

    self.__btn = Button(self, text = "Click on me", command = self.__clicker)
    self.__btn.grid(row = 0, column = 2, columnspan = 2, sticky = W)

    self.__ent = Entry(self)
    self.__ent.grid(row = 3, column = 0, columnspan = 2, sticky = W)

    self.__ent_button = Button(self, text = "Enter", command = self.__input_bold)
    self.__ent_button.grid(row = 3, column = 2, sticky = W)

    self.__fuck_label = Label(self, text = "Hey, bitch")
    self.__fuck_label.grid(row = 5, columnspan = 3)

def __clicker(self):
    self.__clicked += 1
    self.__lbl["text"] = "Button clicked: " + str(self.__clicked)

def __input_bold(self):
    if self.__ent.get() == "Fuck you":
        self.__fuck_label["text"] = "O_0"
    else:
        self.__fuck_label["text"] = "What a fuck did you say?!"


if __name__ == "__main__":

main_window = Tk()

main_window.title("Clicker")
main_window.geometry("200x200")

shell = Shell(main_window)

main_window.mainloop()

假设我们有以下代码：

a = 32
b = a

print(a is b)

如何使 b 成为对内存中新值的引用，而不是 a 引用的值，即 如何使操作print(a is b)打印出来False？