在这里，我们将尝试收集有关 Dart 语言、Flutter 框架和流行库的文献和其他教育资源的最佳答案和推荐。
格式：
Название, Авторы. Год ISBN.
翻译文献格式：
Название, Авторы. Издательство, Год, ISBN.
电子资源以链接的形式呈现。
不要忘记，没有任何理论可以取代编程经验！阅读、尝试、练习。不清楚的话再问。尝试对您的项目进行编程，这是最好的方法。
此列表是社区支持的编程学习资源集合的一部分。
如何在 DataGrid 中显示一定数量的行？例如，只有前 15 个？
<DataGrid x:Name="CsvGrid" ColumnWidth="*" ItemsSource="{Binding csvTable}">
DataTable csvTable = new DataTable();
...
CsvGrid.ItemsSource = csvTable.DefaultView;
数据集进入 DataGrid，并非所有数据都具有相同的列集及其顺序。DataGrid 中的数据是手动显示的，而不是通过 ItemSource 和 DataContext。DataGrid 中的列选择通过复选框进行。
XAML：
<StackPanel Grid.Column="4" Grid.Row="0" x:Name="CheckBoxes"/>
<DataGrid Grid.ColumnSpan="5" Grid.Column="0" Grid.Row="1" x:Name="CsvGrid" ColumnWidth="*" MouseDoubleClick="CsvGrid_OnMouseDoubleClick" ItemsSource="{Binding csvTable}"/>
CheckBoxes 在代码中创建并添加到 StackPanel：
for (int i = 0; i <= count; i++)
{
CheckBox _checks = new CheckBox();
_checks.Tag = fileDataField[i];
_checks.Content = fileDataField[i];
CheckBoxes.Children.Add(_checks);
}
接下来，我想准确保存 CheckBox 中标记的那些列：
CsvGrid.SelectAllCells(); // беру все столбцы
foreach (var checkBox in CheckBoxes.Children.OfType<CheckBox>().Where(x => x.IsChecked == true))
{
for(int i = 0; i < CsvGrid.SelectedCells.Count; i++)
{
if(checkBox.Tag != CsvGrid.Columns[i].Header) //Как удалить лишние ???
}
}
CsvGrid.ClipboardCopyMode = DataGridClipboardCopyMode.IncludeHeader;
ApplicationCommands.Copy.Execute(null, CsvGrid);
String result = (string) Clipboard.GetData(DataFormats.Text);
CsvGrid.UnselectAllCells();
SaveFileDialog saveFileDialog = new SaveFileDialog();
saveFileDialog.FileName = "Document";
saveFileDialog.DefaultExt = ".xls";
saveFileDialog.Filter = "Excel|*.xls|Excel 2010|*.xlsx|CSV files (*.csv)|*.CSV";
saveFileDialog.InitialDirectory =
Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
if (saveFileDialog.ShowDialog() == true) File.WriteAllText(saveFileDialog.FileName, result.Replace(',', ' '));
MessageBox.Show("File created!");
我如何从选择中进入 foreach：
CSVGrid.SelectAllCells();
删除不需要的列？
我有自己写的js库，添加到angular.json中，添加好了。我在 html 文件中使用它：
<div class="video-cover" id="videoPlayer" data-title="{{title.name}} ({{title.year}})"></div>
这就是问题开始的地方，在编译时，由于名称冲突， data-title将其名称更改为title 。因此，JS 停止执行其功能......将名称data-title更改为data-name在编译期间显示错误：
ERROR in : Can't bind to 'data-name' since it isn't a known property of 'div'.
<div ... [ERROR ->]data-name="{{title.name}} ({{title.year}})"></div>
如何解决问题？
我在学一点js，遇到了这么一个奇怪的任务，一方面很有趣，另一方面，看不懂。
编写一个脚本，定期在折叠窗口中显示英文单词及其翻译，然后将其关闭。
问题是：
我使用MaterialDesignInXamlToolkit在 WPF 上开发了一个项目，然后我意识到这个项目需要跨平台。我了解了AvaloniaUI，阅读并喜欢它。但是问题出现了，是否可以将 AvaloniaUI 与 MaterialDesignInXamlToolkit 一起使用？并且，如果可能的话，UI 将如何在不同的平台上显示？
PS我正在Visual Studio 2017上开发
有一个ListView在里面写入数据，事实是没有办法一次把所有的东西都写完，所以需要更改/更新已经输入到ListView中的数据。做这个的最好方式是什么？
<ListView x:Name="ClientsInfo">
<ListView.View>
<GridView>
<GridViewColumn DisplayMemberBinding="{Binding Path=ConnectionID}">ID</GridViewColumn>
<GridViewColumn DisplayMemberBinding="{Binding Path=ClientName}">Name</GridViewColumn>
<GridViewColumn DisplayMemberBinding="{Binding Path=Version}">Version</GridViewColumn>
<GridViewColumn DisplayMemberBinding="{Binding Path=ComputerID}">Computer ID</GridViewColumn>
<GridViewColumn DisplayMemberBinding="{Binding Path=ClientIP}">Client IP</GridViewColumn>
<GridViewColumn DisplayMemberBinding="{Binding Path=PingTime}">Ping Time</GridViewColumn>
</GridView>
</ListView.View>
</ListView>
public class ClientsInfo
{
public string ConnectionID { get; set; }
public string ClientName { get; set; }
public string Version { get; set; }
public string ComputerID { get; set; }
public string ClientIP { get; set; }
public string PingTime { get; set; }
}
ClientsInfo.Items.Add(new ClientsInfo
{
ConnectionID = clientNumber.ToString(),
ClientName = "Receiving...",
Version = "Receiving...",
ComputerID = "Receiving...",
ClientIP = clientIP,
PingTime = "..."
});
ClientsInfo.Items.Refresh();
...
ClientsInfo.Items.Add(new ClientsInfo
{
ClientName = clientsName,
Version = versionStr,
ComputerID = computerName,
});
ClientsInfo.Items.Refresh();
...
ClientsInfo.Items.Add(new ClientsInfo
{
PingTime = $"{elapsedTimeInMilliseconds:0.##}ms"
});
ClientsInfo.Items.Refresh();
有一小段代码，其含义是仅将数组中的数字（其中相似的数字 123.1.512.61 以不同的组合出现）传输到文本框（例如：firstBox.Text 中的 123；secondBox.Text 中的 1 等） . ) . 但是出了点问题，目前我将所有内容都排成一行，一次一个字符（1；2；3；.；等等。）
如何解决？
public void SetByteArray(string userOutput)
{
byte[] userOutputBytes = new byte[4];
if (userOutput != null)
{
userOutputBytes = userOutput.Split(new[] {'.'}, StringSplitOptions.RemoveEmptyEntries)
.Select(s => Convert.ToByte(s, 8))
.ToArray();
}
else
{
userOutput = "123.0.10.321";
userOutputBytes = userOutput.Split(new[] {'.'}, StringSplitOptions.RemoveEmptyEntries)
.Select(s => Convert.ToByte(s, 8))
.ToArray();
}
firstBox.Text = Convert.ToString(userOutput[0]);
secondBox.Text = Convert.ToString(userOutput[1]);
thirdBox.Text = Convert.ToString(userOutput[2]);
fourthBox.Text = Convert.ToString(userOutput[3]);
}
给定一个文本文件，其中包含需要重写到队列 Qu1 的整数图像。在队列 Qu2 中，首先写入回文数，然后是数字和为奇数的数，将其余数写入输出文件。使用 OOP 方法创建程序。
我做了我能做的，但出现了很多错误......我请求你的帮助！
#include "stdafx.h"
#include <iostream>
#include <conio.h>
#include <queue>
#include <fstream>
#include <algorithm>
#include <iterator>
using namespace std;
unsigned getReverse(unsigned n) {
unsigned r = n % 10;
while (n /= 10) {
r = r * 10 + n % 10;
}
return r;
}
bool isPalindrom(const unsigned n) {
return n == getReverse(n);
}
class cQueue
{
protected:
queue<int> p_;
public:
void IO();
void Del()
{
while (!p_.empty())
{
p_.pop();
}
};
};
void cQueue::IO()
{
ifstream ifile("text.txt");
ofstream ofile("output.txt", ios::trunc);
queue<int> qu1 = p_;
for_each(istream_iterator<int>(ifile), istream_iterator<int>(), [&qu1](int n)
{
qu1.push(n);
});
cout << "Number of items in the queue: " << qu1.size() << endl;
while (!qu1.empty())
{
cout << "\nHere they are: " << qu1.front() << '\n';
}
queue<int> qu2;
copy_if(queue<int>(qu1), queue<int>(), queue<int>(qu2), [&qu1](int n) -> bool
{
if (isPalindrom(n)) {
return n;
}
else if (n) {
// Сумма нечетных чисел ?
}
else
{
// В выходной файл ?
}
});
cout << "Number of items in the queue: " << qu2.size() << endl;
while (!qu2.empty())
{
cout << "\nHere they are: " << qu2.front() << '\n';
}
}
int main()
{
cout << "Demo Queue OOP" << endl;
cQueue queue;
queue.IO();
cout << endl;
queue.Del();
_getch();
return 0;
}
错误 C2675 一元“++”：“std::queue>>”未定义此运算符或转换为内置 \algorithm 运算符可接受的类型 594
错误 C2100 无效间接\算法 596
错误 C2100 无效间接\算法 598
错误 C2675 一元 '++': 'std::queue>>' 未定义此运算符或转换为内置 \algorithm 运算符 599 可接受的类型
错误 C4996 'std::copy_if::_Unchecked_iterators::_Deprecate': 使用可能不安全的参数调用 'std::copy_if' - 此调用依赖调用者检查传递的值是否正确。要禁用此警告，请使用 -D_SCL_SECURE_NO_WARNINGS。请参阅有关如何使用 Visual C++ 'Checked Iterators' \algorithm 589 的文档
有必要从列表的前 n 个元素中删除最大的元素。不知何故，我不知道该怎么做。请告诉我该怎么做。
#include "stdafx.h"
#include <iostream>
#include <conio.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
using namespace std;
#define List struct list
List
{
int Dn;
List* Nx;
};
class cList
{
protected:
List* p;
public:
cList() : p(NULL) {}
~cList();
int Empty() { return p == NULL; }
void AddHead(int D)
{
List* q = new(List);
q->Dn = D;
q->Nx = p;
p = q;
}
void Display();
void AddEnd(int D);
long Len();
void DelFirst()
{
List* q = p;
p = p->Nx;
delete(q);
}
};
void cList::Display()
{
List* t = p;
if (p)
while (t)
{
cout << t->Dn << " ";
t = t->Nx;
}
else cout << "->|";
cout << endl;
};
void cList::AddEnd(int D)
{
List* q = new List;
q->Dn = D;
q->Nx = NULL;
List* t = p;
if (p)
{
while (t->Nx) t = t->Nx;
t->Nx = q;
}
else p = q;
};
long cList::Len()
{
if (p)
{
List* t = p;
long i = 0;
while (t)
{
t = t->Nx;
i++;
};
return i;
};
return 0;
};
cList::~cList()
{
while (!Empty()) DelFirst();
};
int main()
{
cout << "Demo List" << endl;
int A[12] = {23, 19, 14, 43, 17, 22, -31, 46, -7, 2, 64, 53};
cList L1;
cout << "The list is empty?:" << L1.Empty() << endl;
L1.Display();
cout << endl;
for (int i = 0; i < 12; i++) L1.AddEnd(A[i]);
L1.Display();
cout << endl;
cout << "Count Element = " << L1.Len() << endl;
L1.~cList();
system("pause");
return 0;
}
因此，我想制作一个带有客户端和服务器的小型 RDP（没有操纵器）。有一个用于创建、压缩、发送和接收图像的小代码。看起来一切都很好，但是即使在局域网上也有野物（尽管正常接收到一半的图像），我还没有通过网络尝试过，我认为它会是一样的。
我没有足够的知识来尽可能优化这段代码，所以我请求你的帮助！
代码：发送 SendStream.cs
using System;
using System.Drawing;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Forms;
namespace Client.Sender
{
public class SendStream
{
private IPEndPoint ipEndPoint;
private UdpClient _udpClient;
private int width;
private int height;
private const UInt16 UdpSize = 65507;
private const UInt16 ControlBlockSize = 5;
private Random random = new Random();
private byte lastA = 0; // Последний код цепочки
private byte lastB = 0; // Последний код цепочки
private float FPS = 60;
public SendStream()
{
// Загружаем номер порта, на которой надо встать
using (StreamReader streamReader = new StreamReader("ip.txt"))
{
string ip = streamReader.ReadLine();
int port = Convert.ToInt32(streamReader.ReadLine());
if (ip != null) ipEndPoint = new IPEndPoint(IPAddress.Parse(ip), port);
}
width = Screen.PrimaryScreen.Bounds.Width;
height = Screen.PrimaryScreen.Bounds.Height;
}
public async Task Run()
{
_udpClient = new UdpClient();
Bitmap backGround = new Bitmap(width, height);
Graphics graphics = Graphics.FromImage(backGround);
while (true)
{
await Task.Delay((int) (1000 / FPS));
graphics.CopyFromScreen(0, 0, 0, 0, new System.Drawing.Size(width, height)); // Получаем снимок экрана
byte[] bytes = ConvertToByte(backGround); // Получаем изображение в виде массива байтов
List<byte[]> data = Package(bytes); // Упаковка изображения в протокол
foreach (var block in data)
{
await _udpClient.SendAsync(block, block.Length, ipEndPoint);
}
}
}
/*
* Конвертируем изображение в массив байтов со сжатием
* Jpeg - качество средние, скорость средние, потери малые (полупрозрачные, 40-60%)
* Gif - качество плохое, скорость максимальное, потери огромные (тв, 90%)
* Png - качество выше-среднего, скорость выше-среднего, потери средние (серый цвет, 40-60%)
*
*/
private byte[] ConvertToByte(Bitmap bmp)
{
MemoryStream memoryStream = new MemoryStream();
bmp.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Gif);
return memoryStream.ToArray();
}
// Пакеты для передачи UDP
private List<byte[]> Package(byte[] bt)
{
int countMsg = (int) Math.Ceiling(bt.Length / (double) UdpSize); // Количество сообщений
List<byte[]> chain = new List<byte[]>(); // Цепочка сообщений
if (countMsg > 65536)
throw new Exception(
"Вы пытаетесь передать сообщение больше 4 ГБ - протокол не подерживает передачу свыше 4 ГБ");
byte[] controlBlock = new byte[ControlBlockSize]; // Формируем контрольный блок
controlBlock[0] = 1;
byte a, b;
do
{
a = (byte) random.Next(0, 256);
b = (byte) random.Next(0, 256);
} while (a == lastA && b == lastB);
// Цикл нужен, чтобы случайно не совпал код сообщений из другой цепочки,
// в одной из параллельных вселенной этот цикл выполняется бесконечно
controlBlock[1] = a;
controlBlock[2] = b;
controlBlock[3] = BitConverter.GetBytes(countMsg)[0];
controlBlock[4] = BitConverter.GetBytes(countMsg)[1];
chain.Add(controlBlock);
int offset = 0;
for (int i = 0; i < countMsg; i++)
{
byte[] msgBlock = new byte[UdpSize]; // Формируем блок сообщения
msgBlock[0] = 0;
msgBlock[1] = a;
msgBlock[2] = b;
msgBlock[3] = BitConverter.GetBytes(i)[0];
msgBlock[4] = BitConverter.GetBytes(i)[1];
int msgBlockLength;
if (bt.Length - offset <= UdpSize)
{
msgBlockLength = bt.Length - offset;
}
else
{
msgBlockLength = UdpSize - 7; // 5 - в данном случае первые 5 байтов
}
msgBlock[5] = BitConverter.GetBytes(msgBlockLength)[0];
msgBlock[6] = BitConverter.GetBytes(msgBlockLength)[1];
if (i == countMsg - 1)
{
Array.Copy(bt, offset, msgBlock, 7, bt.Length - offset);
}
else
{
Array.Copy(bt, offset, msgBlock, 7, UdpSize - 7);
}
chain.Add(msgBlock);
offset += UdpSize;
if (offset > bt.Length)
{
offset = bt.Length;
}
}
return chain;
}
/* Описание протокола передачи LO поверх UDP
1 байт - контрольный пакет (1 если контрольный и 0 если не контрольный)
Расположение байтов для контрольного пакета
2 - 3 байт кодовый номер цепочки пакетов
4 - 5 байт количество пакетов
Расположение байтов для неконтрольного пакета
2 - 3 байт кодовый номер пакета
4 - 5 байт номер пакета
5 - 6 байт размер пакета, а именно данных без первых 6 байт (включая нулевой байт).
*/
}
}
代码：接受 TakeStream.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Media.Imaging;
using System.IO;
namespace Server.Receiving
{
class TakeStream
{
private int TTL = 70; // Время жизни пакетов
private List<Packet> turn = new List<Packet>(); // Очередь сообщений
private List<Packet> controls = new List<Packet>(); // Контрольные пакеты
public delegate void EventReady(BitmapImage img);
public event EventReady FrameReady;
private struct Packet
{
public bool isControl; // Это контрольный пакет?
public UInt16 id; // ID цепочки
public byte[] date; // Данные пакета
public UInt16 count; // Количество пакетов
public UInt16 number; // Порядковый номер пакета
public int TTL; // Длительность жызни пакета или контрола
}
public TakeStream()
{
}
public void addPacked(byte[] data)
{
Packet packet = decodeMsg(data);
if (packet.isControl)
{
controls.Add(packet);
}
else
{
turn.Add(packet);
for (int i = 0; i < controls.Count; i++)
{
if (controls[i].id == packet.id && controls[i].count - 1 == packet.number)
{
MemoryStream ms = new MemoryStream(Compare(packet.id));
controls.RemoveAt(i);
i--;
BitmapImage bitmapImg = new BitmapImage();
bitmapImg.BeginInit();
bitmapImg.CacheOption = BitmapCacheOption.OnLoad;
bitmapImg.StreamSource = ms;
bitmapImg.EndInit();
bitmapImg.Freeze();
FrameReady(bitmapImg);
}
}
}
}
// Сообщение
private Packet decodeMsg(byte[] data)
{
Packet packet = new Packet();
packet.TTL = 0;
packet.isControl = data[0] == 1;
packet.id = BitConverter.ToUInt16(data, 1);
if (packet.isControl)
{
packet.count = BitConverter.ToUInt16(data, 3);
}
else
{
packet.number = BitConverter.ToUInt16(data, 3);
packet.date = new byte[BitConverter.ToUInt16(data, 5)];
try
{
Array.Copy(data, 7, packet.date, 0, packet.date.Length);
}
catch (Exception ex)
{
}
}
return packet;
}
// Исходные данные
private byte[] Compare(UInt16 id)
{
List<byte> data = new List<byte>();
for (int i = 0; i < turn.Count; i++)
{
if (turn[i].id == id)
{
data.AddRange(turn[i].date);
turn.RemoveAt(i);
i--;
}
}
return data.ToArray();
}
private void RemoveChain(UInt16 id)
{
for (int i = 0; i < turn.Count; i++)
{
if (turn[i].id == id)
{
turn.RemoveAt(i);
}
}
}
/* Описание протокола передачи LO поверх UDP
1 байт - контрольный пакет (1 если контрольный и 0 если не контрольный)
Расположение байтов для контрольного пакета
2 - 3 байт кодовый номер цепочки пакетов
4 - 5 байт количество пакетов
Расположение байтов для неконтрольного пакета
2 - 3 байт кодовый номер пакета
4 - 5 байт номер пакета
5 - 6 байт размер пакета, а именно данных без первых 6 байт (включая нулевой байт).
*/
}
}
代码：接受具有给定大小的空 UserControlScreenStream.cs PS 表单
using System;
using System.Text;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Net;
using System.Net.Sockets;
using System.IO;
using PRP_Server.Receiving;
namespace Server.UserControls
{
public partial class UserControlScreenStream : UserControl
{
private UdpClient udpClient;
private const UInt16 UdpSize = 65507;
private const UInt16 ControlBlockSize = 5;
private delegate void AsynkWorker();
private delegate void DrawEvent(BitmapImage bitmapImage);
private delegate void Invoke(byte[] data);
private TakeStream takeStream = new TakeStream();
private UInt16 _port;
public UserControlScreenStream()
{
InitializeComponent();
takeStream.FrameReady += new TakeStream.EventReady(decoder_FrameReady);
new AsynkWorker(Run).BeginInvoke(null, null);
}
void decoder_FrameReady(BitmapImage img)
{
this.Background = new ImageBrush(img);
}
void MainWindow_Invoke(byte[] data)
{
try
{
takeStream.addPacked(data);
}
catch (Exception ex)
{
// ignored
}
}
private void Run()
{
using (StreamReader sr = new StreamReader("port.txt"))
{
_port = UInt16.Parse(sr.ReadLine());
}
UdpClient udp = new UdpClient(new IPEndPoint(IPAddress.Any, _port));
IPEndPoint ep = new IPEndPoint(IPAddress.None, 0);
while (true)
{
byte[] mass = udp.Receive(ref ep);
Dispatcher.Invoke(new Invoke(MainWindow_Invoke), mass);
}
/* byte[] test = new byte[5];
test[0] = 1;
test[1] = 2;
test[2] = 3;
test[3] = 4;
test[4] = 5;
decoder.addPacked(test); */
}
}
}
如何比较字符串（字符串）更大或更小？
我需要做这样的事情： if (fi1 >= fi2); 如果 (fi1 <= fi2); 如果 (fi1 == fi2) ...
private string GetFolderName(string filePath)
{
using (var photo = File.Open(filePath, FileMode.Open, FileAccess.Read))
{
try
{
photo.Flush();
photo.Close();
var fi = new FileInfo(filePath);
var fi1 = fi.CreationTime.ToString(_dirMask);
var fi2 = fi.LastWriteTime.ToString(_dirMask);
if (fi1 == fi2) //if (fi1 >= fi2) как это сделать?
{
return fi1;
}
else return fi2;
}
catch
{
...
}
}
}
我是否正确连接到数据库？
连接时出现错误adapter.Fill(table);
using MySql.Data.MySqlClient;
...
private void buttonOk_Click(object sender, EventArgs e)
{
timer2.Start();
}
public static string Datasource = "localhost";
public static string Port = "3306";
public static string InitialCatalog = "user";
public static string Username = "user";
public static string Password = "pass";
//MySql
MySqlConnection connection = new MySqlConnection("datasource=" + Datasource + ";port=" + Port + ";Initial Catalog='" + InitialCatalog + "';username=" + Username + ";password=" + Password);
MySqlDataAdapter adapter;
DataTable table = new DataTable();
public void MySqlConnect()
{
adapter = new MySqlDataAdapter("SELECT `username`, `password` FROM `users` WHERE `username` = '" + textBoxUsername.Text + "' AND `password` = '" + textBoxPassword.Text + "'", connection);
adapter.Fill(table); //PROBLEM
if (table.Rows.Count <= 0)
{
panel1.Height = 0;
labelMessage.ForeColor = Color.Red;
labelMessage.Text = "Username Or Password Are Invalid";
timer1.Start();
}
else
{
panel1.Height = 0;
labelMessage.ForeColor = Color.Green;
labelMessage.Text = "Login Successfully";
timer1.Start();
}
table.Clear();
}
private void timer1_Tick(object sender, EventArgs e)
{
if (panel1.Height != 100)
{
panel1.Height = panel1.Height + 5;
if (panel1.Height == 100)
{
timer1.Stop();
}
}
}
private void timer2_Tick(object sender, EventArgs e)
{
if (panel1.Height != 0)
{
panel1.Height = panel1.Height - 5;
if (panel1.Height == 0)
{
timer2.Stop();
}
}
}
private void checkBoxShowPass_CheckedChanged(object sender, EventArgs e)
{
if (checkBoxShowPass.Checked)
{
textBoxPassword.UseSystemPasswordChar = true;
}
else
{
textBoxPassword.UseSystemPasswordChar = false;
}
}
...
错误文本
MySql.Data.MySqlClient.MySqlException
HResult=0x80004005
Сообщение = Authentication to host 'localhost' for user 'user' using method 'mysql_native_password' failed with message: Access denied for user 'user'@'localhost' (using password: YES)
Источник = MySql.Data
Внутреннее исключение 1:
MySqlException: Access denied for user 'user'@'localhost' (using password: YES)
将函数从一种形式传递到另一种形式时遇到此问题。如何解决？
登录：
private MainClient OnConnect;
private MainClient OnDataReceived;
private MainClient OnServerDisconnect;
public Login(MainClient OnConnect, MainClient OnDataReceived, MainClient OnServerDisconnect)
{
InitializeComponent();
this.OnConnect = OnConnect;
this.OnDataReceived = OnDataReceived;
this.OnServerDisconnect = OnServerDisconnect;
}
private void buttonLogin_Click(object sender, EventArgs e)
{
...
MainClient._client = new Sock.Client { BufferSize = 1048576 };
MainClient._client.OnConnect += OnConnect; //Problem
MainClient._client.OnDataReceived += OnDataReceived; //Problem
MainClient._client.OnServerDisconnect += OnServerDisconnect; //Problem
...
}
主要的：
...
public static Sock.Client _client = new Sock.Client();
public static ClientInfo _clientInfo = new ClientInfo();
...
private void runLoginScreen()
{
Application.Run(new Login(this, this, this));
}
Не удается неявно преобразовать тип "Project_Name.Main" в "Sock.Client.ServerDisconnectedEventHanlder".代码中标记为“问题”的问题
所以，有一个服务器，你需要不断地、异步地知道它的状态......
这样试了，不行
Thread pingThread = new Thread(_client_PingServer);
pingThread.Start();
private void _client_PingServer()
{
try
{
System.Net.NetworkInformation.Ping ping = new System.Net.NetworkInformation.Ping();
System.Net.NetworkInformation.PingReply pingReply = ping.Send(settingsControl1.txtIPAddress.Text);
if (pingReply.RoundtripTime <= 70 && pingReply.RoundtripTime >= 1)
{
labelServerStatus.ForeColor = System.Drawing.Color.Green;
}
else if (pingReply.RoundtripTime >= 70 && pingReply.RoundtripTime <= 120)
{
labelServerStatus.ForeColor = System.Drawing.Color.Orange;
}
else if (pingReply.RoundtripTime >= 120)
{
labelServerStatus.ForeColor = System.Drawing.Color.Red;
}
else if (pingReply.RoundtripTime == 0)
{
labelServerStatus.Text = @"Offline";
}
if (pingReply.RoundtripTime != 0)
{
labelServerStatus.Text = pingReply.RoundtripTime.ToString();
}
}
catch (PingException)
{
labelServerStatus.ForeColor = System.Drawing.Color.Red;
labelServerStatus.Text = @"Offline";
}
}
你的想法？
锻炼：
诗文（每行不超过 80 个字符）有四行小写。把它写成一个“梯形图”（每行一个单词），在每个四行诗之后插入一个空行。
我的代码：
#include "stdafx.h"
#include <iostream>
#include <string>
#include "conio.h"
using namespace std;
size_t LengthOfUtf8String(const std::string &utf8_string) {
return distance(utf8_string.begin(), utf8_string.end());
}
int main(int argc, const char* argv[])
{
char sub;
int i = 0, n = 0;
string a[80];
string s;
system("CLS");
cout << "Input str" << endl;
cin >> s;
do {
i += 1;
if ((s[i] == ' ') || (s[i] == ',')) {
n += 1;
a[n] = sub;
sub = ' ';
}
else sub = sub + s[i];
} while (!(i == LengthOfUtf8String(s)));
n += 1;
a[n] = sub;
cout << endl;
for (i = 1; i <= n; i++)
{
if (i % 4 == 1) cout << a[i] << endl;
if (i % 4 == 2) cout << ' ' << a[i] << endl;
if (i % 4 == 3) cout << " " << a[i] << endl;
if (i % 4 == 0) {
cout << " " << a[i] << endl;
cout << endl;
}
}
system("pause");
}
问题：我做错了什么？以及应该如何正确完成？
任务：
矩阵旋转。在每个嵌套子矩阵的周长内将给定矩阵的元素顺时针移动一个位置。矩阵NxM。
问： 怎么办？它是一个位置的旋转，也不要忘记子矩阵。
条件说明
Пример (N=3; M=4):
0| 1 | 2 | 3 | 4
=|================
1| 1 2 3 4
2| 5 6 7 8
3| 9 10 11 12
Результат (Как видите 6 и 7 поменяли свое местоположение в своей подматрице, так как матрица 3х4):
0| 1 | 2 | 3 | 4
=|================
1| 5 1 2 3
2| 9 7* 6* 4
3| 10 11 12 8
Пример №2 (N=4; M=4):
0| 1 | 2 | 3 | 4
=|================
1| 1 2 3 4
2| 5 6 7 8
3| 9 10 11 12
4| 13 14 15 16
Результат №2 (Как видите 6, 7, 10, 11 тоже повернулись на один элемент вправо):
0| 1 | 2 | 3 | 4
=|================
1| 5 1 2 3
2| 9 10* 6* 4
3| 13 11* 7* 8
4| 14 15 16 12
"Цифра"* для пояснения
我尝试了一个一维数组，但得出的结论是子矩阵很难组装。 我要考虑的代码：
int main() {
int i, j;
int N;
cout << "Введите размеры матрицы:" << endl;
cout << "N = ";
cin >> N;
cout << "Матрица размером: " << N << "x" << N << endl;
//ДА, я знаю что матрица у меня N на N. Позже она станет размером N на M
int o = N * N;
int k = 0, mas[o];
int **A = new int *[N];
for (i = 0; i < N; i++) {
A[i] = new int[N];
}
int **B = new int *[N];
for (i = 0; i < N; i++) {
B[i] = new int[N];
}
cout << "Введите матрицу:" << endl;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
cin >> A[i][j];
}
}
cout << "Матрица до поворота:" << endl;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
B[i][j] = A[i][j];
cout << B[i][j] << " ";
}
cout << endl;
}
//Тут и нужно сделать поворот матрицы
/*Test*/
cout << "Одномерная матрица:" << endl;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
mas[k++] = B[i][j];
}
}
for (k = 0; k < o; k++) {
cout << mas[k] << " ";
}
cout << endl;
cout << "Сортировка:" << endl;
for (k = 0; k < o - 1; k++) {
int temp = mas[k];
mas[k] = mas[k + 1];
mas[k + 1] = temp;
}
for (k = 0; k < o; k++) {
cout << mas[k] << " ";
}
cout << endl;
k = 0;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
B[i][j] = mas[k++];
}
}
/*Test*/
cout << "Матрица после поворота:" << endl;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
cout << B[i][j] << " ";
}
cout << endl;
}
for (i = 0; i < N; i++) {
delete[] A[i];
delete[] B[i];
}
system("pause");
return 0;
}
有一个文件“io.bin”，其中包含：
ID: 1
Current date and time (time UTC): 05.12.2017 12:09:26
Global time: 00:10:00
ID: 2
Current date and time (time UTC): 06.12.2017 13:04:19
Global time: 00:05:30
ID: 3
...
有代码应该Current date and time (time UTC): 06.12.2017在 textBox 中找到并显示所有内容，直到下一个空格，即：
ID: 2
Current date and time (time UTC): 06.12.2017 13:04:19
Global time: 00:05:30
代码本身：
private static string getDate, setInfo = "info";
...
private void selectDate_Click(object sender, EventArgs e)
{
getDate = dateTimePicker1.Text;
foreach (string line in File.ReadLines("io.bin"))
{
if (line.Contains("Current date and time (time UTC): " + getDate))
{
//тут надо реализовать хождение по строкам, Но как это сделать?
}
StreamReader streamReader = new StreamReader("io.bin");
while (setInfo != null)
{
setInfo = streamReader.ReadLine();
textBox1.Text += setInfo + " \r\n";
}
}
}
UPD：没有完成我的问题。您需要确保这部分代码与您的实现成为朋友
StreamReader streamReader = new StreamReader("io.bin");
while (setInfo != null)
{
setInfo = streamReader.ReadLine();
textBox1.Text += setInfo + " \r\n";
}
也就是说：程序使用if (line.Contains("Current date and time (time UTC): " + getDate))line搜索行Current date and time (time UTC): 05.12.2017，跳过所有其他行，然后获取并复制整个块（从一个空间到另一个空间）。并显示在文本框中
ID: 2
Current date and time (time UTC): 06.12.2017 13:04:19
Global time: 00:05:30
我想将变量（Swt，Srt）从设置表单传递到 Main，并使用它们。问题是当程序启动时，WorkDelay 和 RecreationDelay 被创建为空，以后不会改变。
public static int Swt, Srt;
public TimeSpan WorkDelay = TimeSpan.FromMinutes(Swt); //Work time in minutes
public TimeSpan WorkDelay = TimeSpan.FromMinutes(Swt); //Work time in minutes
主要形式
public partial class Main : Form
{
private DateTime _globalTimeDate;
public static int Swt, Srt;
private DateTime _workExpiry;
public TimeSpan WorkDelay = TimeSpan.FromMinutes(Swt); //Work time in minutes
private DateTime _recreationExpiry;
public TimeSpan RecreationDelay = TimeSpan.FromMinutes(Srt); // Recreation time in minutes
public Main()
{
InitializeComponent();
stop.Enabled = false;
global.Text = @"Stoped";
work.Text = @"Stoped";
recreation.Text = @"Stoped";
}
private void globalTimer_Tick(object sender, EventArgs e)
{
long tick = DateTime.Now.Ticks - _globalTimeDate.Ticks;
DateTime stopWatch = new DateTime();
stopWatch = stopWatch.AddTicks(tick);
global.Text = $@"{stopWatch:HH:mm:ss}";
}
private void workTimer_Tick(object sender, EventArgs e)
{
TimeSpan remaining = _workExpiry - DateTime.Now;
work.Text = remaining.ToString("hh\\:mm\\:ss");
if (work.Text == @"00:00:00")
{
workTimer.Stop();
work.Text = @"Stoped, start recreation";
_recreationExpiry = DateTime.Now.Add(RecreationDelay);
recreationTimer.Start();
}
}
private void recreationTimer_Tick(object sender, EventArgs e)
{
TimeSpan remaining = _recreationExpiry - DateTime.Now;
recreation.Text = remaining.ToString("hh\\:mm\\:ss");
if (recreation.Text == @"00:00:00")
{
recreationTimer.Stop();
recreation.Text = @"Stoped, strart work";
_workExpiry = DateTime.Now.Add(WorkDelay);
workTimer.Start();
}
}
private void start_Click(object sender, EventArgs e)
{
_globalTimeDate = DateTime.Now;
_workExpiry = DateTime.Now.Add(WorkDelay);
globalTimer.Start();
workTimer.Start();
start.Enabled = false;
stop.Enabled = true;
}
private void stop_Click(object sender, EventArgs e)
{
globalTimer.Stop();
workTimer.Stop();
recreationTimer.Stop();
work.Text = @"Stoped";
recreation.Text = @"Stoped";
stop.Enabled = false;
start.Enabled = true;
}
private void exitToolStripMenuItem_Click(object sender, EventArgs e)
{
globalTimer.Stop();
workTimer.Stop();
recreationTimer.Stop();
Application.Exit();
}
private void settingsToolStripMenuItem_Click(object sender, EventArgs e)
{
Settings settings = new Settings();
settings.Show();
}
}
}
设置表格
public partial class Settings : Form
{
public Settings()
{
InitializeComponent();
}
private void buttonSet_Click(object sender, EventArgs e)
{
try
{
Main.Swt = (int) Convert.ToDouble(textBoxW.Text.Replace(',', '.'));
Main.Srt = (int) Convert.ToDouble(textBoxR.Text.Replace(',', '.'));
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
Close();
}
private void buttonReset_Click(object sender, EventArgs e)
{
Main.Swt = 0;
Main.Srt = 0;
}
}
}