小编Hel*_*der的帖子

我在将新数据插入MS Access 2007文件时遇到问题.它说我的SQL语句不正确.

这里有什么问题？我不擅长SQL.请指出我的错误.

            try
            {
                // Open database connection.
                objOleDbConnection.Open();
                objOleDbCommand.CommandText = 
                    "INSERT INTO PersonalData (Type, UserName, Password) VALUES ('" + cmbType.Text + "','" + txtUserName.Text + "','" + txtPassword.Text + "')";
                // Execute creating table command.
                objOleDbCommand.ExecuteNonQuery();
            }

我一直在玩,写下这段小代码.我试图翻转硬币定义的次数,然后计算我得到多少尾巴和头.所以这里是:

private void Start_Click(object sender, EventArgs e)
{
    int headss = 0;
    int tailss = 0;
    int random2, g;
    string i = textBox1.Text;
    int input2, input;
    bool NumberCheck = int.TryParse(i, out input2);

    if (textBox1.Text == String.Empty) // check for empty string, when true
        MessageBox.Show("Enter a valid number between 0 and 100000.");
    else // check for empty string, when false
        if (!NumberCheck) // number check, when false
        {
            textBox1.Text = String.Empty;
            MessageBox.Show("Enter a valid number between 0 and 100000.");
        }
        else …

我有2个按钮.我试图将按钮1中的事件用于按钮2,这样他们都可以做同样的事情.
因此,通过单击2,按钮1也会被单击.我实际上是从菜单条项目这样做,但我认为它具有相同的原则.我只是不想有重复的代码.我认为button1.Click()可以工作,但显然它没有.我怎么能这样做？

简化示例:

private void button1_Click(object sender, EventArgs e)
{
    count += 1;
    label1.Text = Convert.ToString(count);
}
private void button2_Click(object sender, EventArgs e)
{
    count += 1;
    label1.Text = Convert.ToString(count);
}

- 编辑 -

我使用的是一个类图,它没有显示任何可以/应该执行此操作的其他方法.需要坚持类图.

我正在尝试在我的数据库中创建一个表,我被告知我的SQL语法有错误.而我无法分辨到哪里.

objOleDbCommand.CommandText = "CREATE TABLE PersonalData (" +
    "[DataID] AUTOINCREMENT NOT NULL PRIMARY KEY ," +
    "[Type] VARCHAR(40) NOT NULL ," +
    "[URL] VARCHAR(40) NOT NULL ," +
    "[SoftwareName] VARCHAR(40) NOT NULL ," +
    "[SerialCode] VARCHAR(40) NOT NULL ," +
    "[UserName] VARCHAR(40) NOT NULL ," +
    "[Password] VARCHAR(40) NOT NULL";

objOleDbCommand.ExecuteNonQuery();

我正在努力选择一个会导致删除所选项目的项目.问题是,当我删除一个项目时,我正在选择导致另一个删除的附加项目...

删除所选项目后如何取消选择/取消选择？

这导致了我的问题:

    void lbMessage_SelectedIndexChanged(object sender, EventArgs e)
    {
        DialogResult result = new DialogResult();

        result = MessageBox.Show("Are you sure you want to remove this item?", "Removal Confirmation", MessageBoxButtons.YesNo, MessageBoxIcon.Information);

        if (result == DialogResult.Yes)
        {
            lbMessage.Items.Remove(lbMessage.SelectedItem); 
            lbMessage.SelectedIndex = -1;
        }
        else
        {
        }
    }

    private void btnAddMessage_Click(object sender, EventArgs e)
    {
        lbMessage.Items.Add(txtMessage.Text);
        txtMessage.Text = string.Empty;
    }

我想显示从ListBox到TextBox的所有元素.我不知道如何做到这一点,我尝试过做foreach语句,但由于ListBox不包含IEnumerator,它不起作用.

这该怎么做？

我正在尝试将IP地址转换为MAC地址,然后将其转换为字节数组.我陷入了第一部分而不确定如何做到这一点.我看到一些搜索结果在谈论System.Net.NetworkInformation.NetworkInterface但不确定如何使用它.

这是我需要MAC字节数组的代码.这该怎么做？

[DllImport("iphlpapi.dll", ExactSpelling = true)]
public static extern int SendARP(int DestIP, int SrcIP, byte[] pMacAddr, ref uint PhyAddrLen);

private void Ping(IPAddress address)
{
    byte[] macAddr = new byte[6];
    uint macAddrLen = uint.Parse(macAddr.Length.ToString());

    if (SendARP(int.Parse(address.ToString()), 0, macAddr, ref macAddrLen) == 0)
    {
        //SUCCESS!
    }
}

我正在用C++编写一个家庭作业的程序.将值从一个初始化构造函数传递给另一个,我遇到了一些问题,它说:

error C2664: 'Book::Book(std::string,Author *,Publisher *,double)' : cannot convert parameter 2 from 'Author' to 'Author *'

我在OOP中有点生疏,也是C++的新手.

如果我应该包含更多代码,请发布我将附加来自主要类和类的代码,我无法进行转换.该计划尚未完成.

Main.cpp的

#include <iostream>
using namespace std;

#include "Book.h"

void main()
{
    cout << "Book 1" << endl;

    Author *pAuthor = new Author("John", "Doe");
    Publisher *pPublisher = new Publisher("Wrox", "10475 Crosspoint Blvd.", "Indianapolis");
    Book *book = new Book("Memory Management", *pAuthor, *pPublisher, 49.99);

    cout << "Book 2" << endl;
    int i;
    cin >> i;
};

我构建了这个代码,以队列方式显示数组的所有条目.问题是,我被告知这可以在没有for声明的情况下完成,将内容倒i回到0,但我无法弄清楚如何.

怎么可以做到这一点？

   public void display()
   {
       int i = frontIndex;

       while(true)
       {
           if (i == numberOfItems)
               i = 0;

           System.out.print(array[i++] + " ");

           if (i == rearIndex + 1)
               break;
       }
   }

我收到一个错误:

Exception in thread "main" java.lang.StackOverflowError
    at CreateCardDeck.<init>(CreateCardDeck.java:6)
    at CardStack.<init>(CardStack.java:7)
    at CreateCardDeck.<init>(CreateCardDeck.java:8)
    at CardStack.<init>(CardStack.java:7)
    at CreateCardDeck.<init>(CreateCardDeck.java:8)
    ...
    ...
    ...
    at CardStack.<init>(CardStack.java:7)
    at CreateCardDeck.<init>(CreateCardDeck.java:8)

But I don't understand why there would be an error. In my code I have specified amount of cards etc. So what would be the problem here?

public class CreateCardDeck
{
    int deckSize = 52;
    CardStack cardStack;

    CreateCardDeck()
    {
        cardStack = new CardStack(deckSize); --------------- problem here -----
    }
}

And

class CardStack extends CreateCardDeck
{
    public CardStack(int …