仕事メモです。
Windowsプログラミングによく使用するMessageBox。大量の内容を見せやすくするには改行が必要不可欠です。
いちいちCrLfを追加するのが面倒くさいので、より分かりやすくなる名前はC#内にあるようです。
Environment.NewLine
上記の意味ある内部変数を使ったらいいです。将来LinuxやMacに変更しても同じもので対応可能。通常のCrLfはWindowsのみであり、OSによる覚え間違いは減りますが、長い英単語を覚える方が逆に難しい…なんです。
長い間ウワサは聞いておりますが、初めて触りました。リートコード(LeetCode)という中国発のネットジャージシステム。一応自分が登録したのはアメリカサーバですけどね。
多分アルゴリズム上ではそこまで最適化していませんが、一応コードを記録しておくことに：
public class Solution {
public int[] TwoSum(int[] nums, int target) {
int index1=0;
int index2=1;
int maxindex = nums.Length;
while (true)
{
int solution = nums[index1] + nums[index2];
if (solution == target)
{
int[] result = new int[] { index1, index2 };
return result;
}
index2++;
if(index2 >= maxindex)
{
index1++;
index2 = index1 + 1;
}
}
}
}
warning NU1604: Project dependency 'PackageA' (<= 9.0.0) does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
Solution檔案夾下放一個共通的檔案。如果你像我常常使用VSCode，那就是把檔案放在sln檔的同一個目錄中。在標準設定中，他會被叫做Directory.Build.props<Project>
<PropertyGroup Label="Package Dependencies">
<AspNetCoreVersion>5.0</AspNetCoreVersion>
<EntityFrameworkVersion>5.0</EntityFrameworkVersion>
<BlazorVersion>5.0</BlazorVersion>
<SystemNetHttpJsonVersion>5.0</SystemNetHttpJsonVersion>
</PropertyGroup>
</Project>
<Project>的最上層添加下面這行<import Project="..\Directory.Build.props" />DataGridCheckBoxColumn裡的CheckBox，在預設狀態下，必須先點一次，Row取得focurs之後才能改變狀態。使用上不是很直覺，跟一般的CheckBox不太一樣。
背後的原因是因為DataGridCell本身有分成顯示用的ElementStyle跟編輯用的EditElementStyle兩種模式，為了做出區分，犧牲了CheckBox的直覺性。
可以依靠設定Style的方法，使操作更為直覺。
<Style TargetType="CheckBox" x:Key="CellCheckBoxStyle" BasedOn="{StaticResource {x:Type CheckBox}}" />
<DataGridCheckBoxColumn Binding="{Binding Selected}" ElementStyle="{StaticResource CheckBoxCellStyle}" />
做完以上的設定，指定的DataGridCheckBoxColumn裡面的CheckBox就會是我們常用的單點就會有反應的CheckBox了。
以上。這是一連串的文章，關於我所知道的C#推廣者 Tim Corey 頻道 IAmTimCorey 的內容。
這同時是我的學習筆記。以下的中文用詞，大部分是個人慣用語。一般來說會附上英文原詞，方便大家對照。
原始連結: https://www.youtube.com/watch?v=qv6ZflueASY
這次的題目，是有關那個號稱地表最強IDE的Visual Studio在設定上的一些小技巧與內容。
a+b但是在LISP裡面，你必須寫成像這樣
(+ a b)
A*B必須寫成
(* A B)
f(x)而在LISP之中，他會看起來像是
(f x)直接將引數放在函數名後面，很容易理解吧
f(x,y)而在LISP中，他會看起來像是
(f x y)非常直覺，很好
sqlite-jdbc-3.8.7.jarimport java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.sqlite.JDBC;
public class JavaSQLiteTest {
public static void main(String[] args) throws ClassNotFoundException {
// load the sqlite-JDBC driver using the current class loader
//Class.forName("org.sqlite.JDBC"); // you can use this if you don't use the import.
Connection connection = null;
try{
connection = DriverManager.getConnection("jdbc:sqlite:sample.db");
Statement stm = connection.createStatement();
stm.setQueryTimeout(30); // set timeout to 30 sec.
stm.executeUpdate("drop table if exists person");
stm.executeUpdate("create table person (id integer, name string)");
stm.executeUpdate("insert into person values(1,'leo')");
stm.executeUpdate("insert into person values(2,'yui')");
ResultSet rs = stm.executeQuery("select * from person");
while(rs.next()){
// read the result set
System.out.println("name = " + rs.getString("name"));
System.out.println("id = " +rs.getInt("id"));
}
}catch(SQLException e){
// if the error message is "out of memory",
// it probably means no database file is found
System.err.println(e.getMessage());
}finally{
try{
if(connection != null)
connection.close();
}catch(SQLException e){
// connection close failed.
System.err.println(e);
}
}
}
}
org.sqlite.JDBC" showed in "Driver Class", and the Name field is "SQLite".jdbc:sqlite:sample.db
3. Done.
| 典型指令之執行 execute typical instruction | 1/1,000,000,000 sec = 1 nanosec |
| 從L1快取獲取資料 fetch from L1 cache memory | 0.5 nanosec |
| 分歧預測失誤 branch misprediction | 5 nanosec |
| 從L2快取獲取資料 fetch from L2 cache memory | 7 nanosec |
| 互斥鎖定/解鎖 Mutex lock/unlock | 25 nanosec |
| 從主記憶體獲取資料 fetch from main memory | 100 nanosec |
| 從1Gbps頻寬的網路傳送2K bytes資料 send 2K bytes over 1Gbps network | 20,000 nanosec |
| 從記憶體循序讀取1MB資料 read 1MB sequentially from memory | 250,000 nanosec |
| 取得新磁碟位址(搜尋) fetch from new disk location (seek) | 8,000,000 nanosec |
| 從磁碟循序讀取1MB資料 read 1MB sequentially from disk | 20,000,000 nanosec |
| 將封包從美國送到歐洲再傳回 send packet US to Europe and back | 150 milliseconds = 150,000,000 nanosec |
CenterWinDialog by Hans Passantusing System;
using System.Text;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
class CenterWinDialog : IDisposable {
private int mTries = 0;
private Form mOwner;
public CenterWinDialog(Form owner) {
mOwner = owner;
owner.BeginInvoke(new MethodInvoker(findDialog));
}
private void findDialog() {
// Enumerate windows to find the message box
if (mTries < 0) return;
EnumThreadWndProc callback = new EnumThreadWndProc(checkWindow);
if (EnumThreadWindows(GetCurrentThreadId(), callback, IntPtr.Zero)) {
if (++mTries < 10) mOwner.BeginInvoke(new MethodInvoker(findDialog));
}
}
private bool checkWindow(IntPtr hWnd, IntPtr lp) {
// Checks if <hwnd> is a dialog
StringBuilder sb = new StringBuilder(260);
GetClassName(hWnd, sb, sb.Capacity);
if (sb.ToString() != "#32770") return true;
// Got it
Rectangle frmRect = new Rectangle(mOwner.Location, mOwner.Size);
RECT dlgRect;
GetWindowRect(hWnd, out dlgRect);
MoveWindow(hWnd,
frmRect.Left + (frmRect.Width - dlgRect.Right + dlgRect.Left) / 2,
frmRect.Top + (frmRect.Height - dlgRect.Bottom + dlgRect.Top) / 2,
dlgRect.Right - dlgRect.Left,
dlgRect.Bottom - dlgRect.Top, true);
return false;
}
public void Dispose() {
mTries = -1;
}
// P/Invoke declarations
private delegate bool EnumThreadWndProc(IntPtr hWnd, IntPtr lp);
[DllImport("user32.dll")]
private static extern bool EnumThreadWindows(int tid, EnumThreadWndProc callback, IntPtr lp);
[DllImport("kernel32.dll")]
private static extern int GetCurrentThreadId();
[DllImport("user32.dll")]
private static extern int GetClassName(IntPtr hWnd, StringBuilder buffer, int buflen);
[DllImport("user32.dll")]
private static extern bool GetWindowRect(IntPtr hWnd, out RECT rc);
[DllImport("user32.dll")]
private static extern bool MoveWindow(IntPtr hWnd, int x, int y, int w, int h, bool repaint);
private struct RECT { public int Left; public int Top; public int Right; public int Bottom; }
}
private void button1_Click(object sender, EventArgs e) {
using (new CenterWinDialog(this)) {
MessageBox.Show("Nobugz waz here");
}
}
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
internal static class MessageBoxHelper
{
internal static void PrepToCenterMessageBoxOnForm(Form form)
{
MessageBoxCenterHelper helper = new MessageBoxCenterHelper();
helper.Prep(form);
}
private class MessageBoxCenterHelper
{
private int messageHook;
private IntPtr parentFormHandle;
public void Prep(Form form)
{
NativeMethods.CenterMessageCallBackDelegate callBackDelegate = new NativeMethods.CenterMessageCallBackDelegate(CenterMessageCallBack);
GCHandle.Alloc(callBackDelegate);
parentFormHandle = form.Handle;
messageHook = NativeMethods.SetWindowsHookEx(5, callBackDelegate, new IntPtr(NativeMethods.GetWindowLong(parentFormHandle, -6)), NativeMethods.GetCurrentThreadId()).ToInt32();
}
private int CenterMessageCallBack(int message, int wParam, int lParam)
{
NativeMethods.RECT formRect;
NativeMethods.RECT messageBoxRect;
int xPos;
int yPos;
if (message == 5)
{
NativeMethods.GetWindowRect(parentFormHandle, out formRect);
NativeMethods.GetWindowRect(new IntPtr(wParam), out messageBoxRect);
xPos = (int)((formRect.Left + (formRect.Right - formRect.Left) / 2) - ((messageBoxRect.Right - messageBoxRect.Left) / 2));
yPos = (int)((formRect.Top + (formRect.Bottom - formRect.Top) / 2) - ((messageBoxRect.Bottom - messageBoxRect.Top) / 2));
NativeMethods.SetWindowPos(wParam, 0, xPos, yPos, 0, 0, 0x1 | 0x4 | 0x10);
NativeMethods.UnhookWindowsHookEx(messageHook);
}
return 0;
}
}
private static class NativeMethods
{
internal struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
}
internal delegate int CenterMessageCallBackDelegate(int message, int wParam, int lParam);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool UnhookWindowsHookEx(int hhk);
[DllImport("user32.dll", SetLastError = true)]
internal static extern int GetWindowLong(IntPtr hWnd, int nIndex);
[DllImport("kernel32.dll")]
internal static extern int GetCurrentThreadId();
[DllImport("user32.dll", SetLastError = true)]
internal static extern IntPtr SetWindowsHookEx(int hook, CenterMessageCallBackDelegate callback, IntPtr hMod, int dwThreadId);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool SetWindowPos(int hWnd, int hWndInsertAfter, int X, int Y, int cx, int cy, int uFlags);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
}
}
private void button1_Click(object sender, EventArgs e)
{
MessageBoxHelper.PrepToCenterMessageBoxOnForm(this);
MessageBox.Show("Hello!", "Hello!", MessageBoxButtons.OK, MessageBoxIcon.None, MessageBoxDefaultButton.Button1, 0);
}
DataTable.dt, and I link it to a DataGridView dgvdgv.DataSource = dt;
DataGridView.EndEdit().DataGridView.EndEdit().CurrentCelldgv.EndEdit(); dgv.CurrentCell = null;
sqlConnectString for default connection, and we try to access all columns of demoTable. There is a global DataTable named dt.string sql = @"SELECT * FROM demoTable;";
using(var conn = new SQLConnection(sqlConnectString))
{
conn.Open();
using(var cmd = new SQLCommand(conn))
{
cmd.CommandText = sql;
var reader = cmd.ExecuteReader();
dt.Load(reader);
}
}
2. to update DataTable's data to Database
string sql = @"SELECT * FROM demoTable;";
using(var conn = new SQLConnection(sqlConnectString))
{
conn.Open();
var adp = new SQLDataAdapter(sql, conn);
var cmb = new SQLCommandBuilder(adp);
adp.Update(dt);
}
getdate()函式。getdate() 所提取的內容與current_timestamp將會相同SELECT current_timestamp "Standard Timestamp", getdate() 'Transact-SOL datetime'
datepart()可以提取getdate()所提供的變數中的特定欄位的內容datepart(year, getdate())可以提取年份的資料CREATE TEMPORARY TABLE temp_table ENGINE=MEMORY SELECT * FROM your_table WHERE id=1; UPDATE temp_table SET id=NULL; /* Update other values at will. */ INSERT INTO your_table SELECT * FROM temp_table; DROP TABLE temp_table;
SELECT * INTO temp_table FROM your_table WHERE id=1 ; UPDATE temp_table SET id=NULL; /* Update other values at will. */ INSERT INTO your_table SELECT * FROM temp_table; DROP TABLE temp_table;
SELECT xxx FROM yyy WHERE zzz)，然後靠JDBC自動抓取db的內容來設定field，然後把那些Field丟進表單中HashMap parameters = new HashMap();
parameters.put("FIELD1", something);
JasperFillManager.fillReportToFile(JASPER檔案路徑, parameters, 某某資料庫的Connection);
$F{FIELDS}要改成$P{FIELDS}Connection改成Datasource，然後把原來Java裡面的內容靠Datasource丟進去。Datasource用的Javabean。在這個例子裡，我叫他Studentpublic class Student {
private String name;
private String serialNo;
private List scores;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSerialNo() {
return serialNo;
}
public void setSerialNo(String serialNo) {
this.serialNo = serialNo;
}
public List getScores() {
return scores;
}
public void setScores(List scores) {
this.scores = scores;
}
}
public class Score {
private Integer point;
private String name;
public Integer getPoint() {
return point;
}
public void setPoint(Integer point) {
this.point = point;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
public class ContentFactory {
static public List create(){
List fakelist = new ArrayList<>();
Student fakeStudent1 = new Student();
fakeStudent1.setName("孫甲");
fakeStudent1.setSerialNo("A001");
List fakeScoreList1 = new ArrayList<>();
Score fakeScore1 = new Score();
fakeScore1.setName("國語");
fakeScore1.setPoint(76);
Score fakeScore2 = new Score();
fakeScore2.setName("數學");
fakeScore2.setPoint(100);
fakeStudent1.setScores(fakeScoreList1);
fakelist.add(fakeStudent1);
return fakelist;
}
}
JasperFillManager.fillReportToFile("reports/epsSinglePageOutput.jasper", parameters, new JRBeanCollectionDataSource(ContentFactory.create()));
new net.sf.jasperreports.engine.JREmptyDataSource(1)new net.sf.jasperreports.engine.data.JRBeanCollectionDataSource($F{scores})LAST_INSERT_ID(). SELECT LAST_INSERT_ID()
