我做了一些测试IList<T>.Aggregate(),但答案对我来说没有意义.
List<int> Data1 = new List<int> { 1,0,0,0,0};
var result = Data1.Aggregate<int>((total, next) => total + total);
结果是16.
我期待它32.
谁能解释一下？
如果我们将填充声明为const十进制,则填充不起作用.
mymoney = 1.2而你的钱= 1.20,这个行为怎么解释？
class Program
{
static void Main(string[] args)
{
decimal balance = 1.2m;
const decimal ConstPadding = 0.00m;
decimal padding = 0.00m;
decimal mymoney = decimal.Round(balance + ConstPadding, 2);
decimal yourmoney = decimal.Round(balance + padding, 2);
Console.WriteLine(mymoney); // 1.2
Console.WriteLine(yourmoney); //1.20
}
}
我正在进行测试.
看起来像:
方法1)
List<int> = new List<int>{1,2,4, .....} //assume 1000k
var result ErrorCodes.Where(x => ReturnedErrorCodes.Contains(x)).First();
方法2)
List<int> = new List<int>{1,2,4, .....} //assume 1000k
var result = ErrorCodes.Where(x => ReturnedErrorCodes.Contains(x)).ToArray()[0];
为什么方法2与方法1相比是如此之慢？
为什么在C#中我的两个变量指向不同的DateTime对象？
DateTime a1 = DateTime.Now;
DateTime a2 = a1;
a1 = a1 + TimeSpan.FromMinutes(15);
a2 = a2 - TimeSpan.FromMinutes(16);
我意识到a2实际上指的是一个与a1不同的新对象.
但在其他情况下.假设我有一个人类,年龄= 1;
Person a1 = new Person();
a2 = a1;
a2 = Person.Age = 2;
在Person Case中,a1和a2指向同一个对象.我真的很困惑,有人可以解释一下吗？
new构造函数和new成员声明之间有什么区别？
例
public class PspGame {
private List<string>name = new List<string>();
private List<string>_value;
public PspGame() {
_value = new List<string>();
}
}
最好的方法是什么,是否有任何性能问题？
我有一个数据库项目,目前正在使用"dbo"架构.我想将dbo更新为其他内容.
我能够找到项目设置来更改默认的dbo模式名称,但它只适用于新添加的表.如何将现有表从dbo更新为其他内容.
请帮我,
string myNumber = "3.44";
Regex regex1 = new Regex(".");
string[] substrings = regex1.Split(myNumber);
foreach (var substring in substrings)
{
Console.WriteLine("The string is : {0} and the length is {1}",substring, substring.Length);
}
Console.ReadLine();
我试图用"."拆分字符串,但是拆分返回4个空字符串.为什么？
这是我的问题.我有一个类游戏,我想将一些成员绑定到datagrid,而不是整个对象.有什么更好的方法呢？创建另一个对象以保存信息,或创建数据表？
public class Game
{
public string Name {get;set; }
public string Description {get;set;}
public string FullPath {get;set;}
}
List<Game> Games = new Games { game1, game2, game3 };
dataGrid1.ItemsSource = Game; // I don't want to do this it will bind entire object.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace ThreadExample
{
public class Info
{
public int Counter;
private static object _lock = new object();
private List<Thread> ThreadList;
public Info(int counter)
{
Counter = counter;
ThreadList = new List<Thread>();
ThreadList.Add(new Thread(ThreadBody));
ThreadList.Add(new Thread(ThreadBody));
ThreadList[0].Name = "t1";
ThreadList[1].Name = "t2";
}
public void Start()
{
ThreadList.ForEach(t => t.Start(t.Name));
}
public void ThreadBody(object name)
{
while (Counter != 20)
{
lock (_lock)
{
Counter++;
Console.WriteLine("Thread {0} : the value of …我是WPF的菜鸟.希望我能找到答案.
例如,我有一个List<Customer>,它绑定到dataGrid.如果我将新客户添加到列表中,并且我没有看到datagrid在那里添加新行.
<DataGrid ItemsSource="{Binding Customers}" AutoGenerateColumns="False" Height="318">
<DataGrid.Columns>
<DataGridTextColumn Header="First Name" Binding="{Binding FirstName, Mode=TwoWay}" />
<DataGridTemplateColumn Header="Image" Width="SizeToCells" IsReadOnly="True">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Image Height="80" Source="{Binding Image,Mode=TwoWay}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
using System.Windows.Data;
namespace DataGrid
{
public class MainWindowViewModel
{
public ICollectionView Customers { get; private set; }
public ICollectionView GroupedCustomers { get; private set; }
public List<Customer> _customers { get; set; }
public MainWindowViewModel()
{
_customers … class StreamReaderWriterDemo : AbastractDemo
{
public override void Run()
{
string message = "hello this is a test 0000";
string result = string.Empty;
try
{
using (var memoryStream = new MemoryStream())
{
StreamWriter streamWriter = new StreamWriter(memoryStream, Encoding.Default);
this.WriteToStream(streamWriter, memoryStream, message);
memoryStream.Position = 0;
StreamReader streamReader = new StreamReader(memoryStream, Encoding.Default);
result = this.ReadFromStream(streamReader, memoryStream);
streamWriter.Dispose();
streamReader.Dispose();
}
}
catch (Exception ex)
{
}
Console.WriteLine(result);
}
private void WriteToStream(StreamWriter streamWriter, MemoryStream stream, string message)
{
streamWriter.Write(message);
streamWriter.Flush();
streamWriter.Close();
}
private string …