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Tabla de Contenidos

C# code snippets

C# code snippets

Trabajo con datos

Conversiones

De byte a String

new System.Text.ASCIIEncoding().GetString( xxxxxxxxxxxx );

De String a byte

new System.Text.ASCIIEncoding().GetBytes( xxxxxxxxxxxx );

De unicode a String

Encoding.UTF8.GetString(myByteArray))

Arrays

Podemos limpiar un array con el método estático Array.Clear.
Los elementos IQueryable<>, esos que provienen de consultas con LINQ, tienen métodos tan útiles como ToList o ToArray.

Fechas

Diferencia de fechas

DateTime oldDate = new DateTime(2002,7,15);
DateTime newDate = DateTime.Now;
// Difference in days, hours, and minutes.
TimeSpan ts = newDate - oldDate;
// Difference in days.
int differenceInDays = ts.Days;
System.Console.WriteLine("Difference in days: {0} ", differenceInDays);

Trabajar con ficheros

Leer

String sFile = @"c:\matriu2.txt";
StreamReader re = File.OpenText(sFile);
string input = null;
while ((input = re.ReadLine()) != null)
{}
re.Close();

Escribir

FileInfo t = new FileInfo(@"c:\matriu3.txt");
StreamWriter sw = t.CreateText();
sw.WriteLine("hola");
sw.Close();

Otra alternativa de declaración:

StreamWriter sw = new StreamWriter(File.Open(sFile, FileMode.Create, FileAccess.Write, FileShare.ReadWrite));

Escribir en UTF8

System.IO.TextWriter tw = new System.IO.StreamWriter(
    new System.IO.FileStream(path + "\\index.html", System.IO.FileMode.Create),
    System.Text.Encoding.UTF8);
tw.Write(body);
tw.Close();

XML

Abrir archivos para lectura, con la referencia System.Xml agregada:

XmlDocument doc = new XmlDocument();
doc.Load(path);

Coger nodos por nombre:

XmlNode mainNode = doc.GetElementsByTagName("kvtml")[0];

Coger nodos hijo:

XmlNodeList nodes = mainNode.ChildNodes;

Coger texto interno:

foreach (XmlNode node in nodes)
{
   lang1 = node.ChildNodes[0].InnerText;
}

Expresiones regulares

Eliminar las tags de un texto

using System.Text.RegularExpressions;
public string Strip(string text)
{
    return Regex.Replace(text, @”<(.|\n)*?>”, string.Empty);
}

Descargar archivos de internet

System.Net.WebClient wc = new System.Net.WebClient();
wc.DownloadFile("http://url/imagen.jpg", "c:\\img.jpg");

Trabajo con el Sistema Operativo

Windows.Forms

Asignar un DataList a un combo

DataTable list = new DataTable(); 
list.Columns.Add(new DataColumn("telf", typeof(string)));  
list.Columns.Add(new DataColumn("Id", typeof(int)));  
 
for(int w=0;w<(ret.filas);w++) {
	list.Rows.Add(list.NewRow());
	list.Rows[w][0] = "("+ret.getCell(w,ret.getNumCell("tel_area"))+")(" + 
		ret.getCell(w,ret.getNumCell("tel_region"))+") "
		+ret.getCell(w,ret.getNumCell("tel_numero")); 
	list.Rows[w][1] = System.Convert.ToInt32(ret.getCell(w, 
		ret.getNumCell("tel_sectel")));
}
 
this.cmbInt.DataSource = list;  
this.cmbInt.DisplayMember = "telf";  
this.cmbInt.ValueMember = "Id";

Saber control activo en un formulario

private void DisplayNameOfActiveControl() {
    label1.Text = this.ActiveControl.Name;
}

Enlazar un array a un listbox

listBox1.DataSource = new string[] { "one", "two", "three" };

Llamar al click de un botón

private void button2_Click(object sender, System.EventArgs e) {
  button1.PerformClick();
};

Creación de aplicaciones

Cambiar forma de ventana

protected override void OnPaint( System.Windows.Forms.PaintEventArgs e ) {
    System.Drawing.Drawing2D.GraphicsPath shape = new System.Drawing.Drawing2D.GraphicsPath();
    shape.AddEllipse(0, 0, this.Width, this.Height);
    this.Region = new System.Drawing.Region(shape);
}

Podemos crear un formulario con forma mediante un png dibujado por código, drawImage, sobre un formulario sin bordes con un transparencekey.

Acceder al portapapeles

Clipboard.SetDataObject(textBox1.Text);
textBox1.Text = ClipBoard.GetDataObject();

Listar todos los archivos de un directorio

string[] str = Directory.GetFiles(“C:\\Windows”);

Menú contextual

private void Form1_Load(object sender, System.EventArgs e) {
    System.Windows.Forms.ContextMenu contextMenu1;
    contextMenu1 = new System.Windows.Forms.ContextMenu();
    System.Windows.Forms.MenuItem menuItem1;
    menuItem1 = new System.Windows.Forms.MenuItem();
    System.Windows.Forms.MenuItem menuItem2;
    menuItem2 = new System.Windows.Forms.MenuItem();
    System.Windows.Forms.MenuItem menuItem3;
    menuItem3 = new System.Windows.Forms.MenuItem();
 
    contextMenu1.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {menuItem1, menuItem2, menuItem3});
    menuItem1.Index = 0;
    menuItem1.Text = "MenuItem1";
    menuItem2.Index = 1;
    menuItem2.Text = "MenuItem2";
    menuItem3.Index = 2;
    menuItem3.Text = "MenuItem3";
 
    textBox1.ContextMenu = contextMenu1;
}

Seleccionar unas fechar en un control Calendar

private void monthCalendar1_DateSelected(object sender, System.Windows.Forms.DateRangeEventArgs e) {
    DateTime startDate = e.Start;
    startDate = startDate.AddDays(-(double)startDate.DayOfWeek);
    monthCalendar1.SelectionStart = startDate;
    monthCalendar1.SelectionEnd = startDate.AddDays(6);
}

Crear un botón no rectangular

public Form1() {
  InitializeComponent();
  myButtonObject myButton = new myButtonObject();
  EventHandler myHandler = new EventHandler(myButton_Click);
  myButton.Click += myHandler;
  myButton.Location = new System.Drawing.Point(20, 20);
  myButton.Size = new System.Drawing.Size(101, 101);
  this.Controls.Add(myButton);
}
public class myButtonObject : UserControl {
  protected override void OnPaint(PaintEventArgs e) {
      Graphics graphics = e.Graphics;
      Pen myPen = new Pen(Color.Black);
      graphics.DrawEllipse(myPen, 0, 0, 100, 100);
      myPen.Dispose();
  }
 
  public void myButton_Click(Object sender, System.EventArgs e) {
    MessageBox.Show("Click");
  }
}

Impresiones

Imprimir formulario

[System.Runtime.InteropServices.DllImport("gdi32.dll")]
public static extern long BitBlt (IntPtr hdcDest, int nXDest, int nYDest, int nWidth, int nHeight, IntPtr hdcSrc, int nXSrc, int nYSrc, int dwRop);
private Bitmap memoryImage;
private void CaptureScreen() {
   Graphics mygraphics = this.CreateGraphics();
   Size s = this.Size;
   memoryImage = new Bitmap(s.Width, s.Height, mygraphics);
   Graphics memoryGraphics = Graphics.FromImage(memoryImage);
   IntPtr dc1 = mygraphics.GetHdc();
   IntPtr dc2 = memoryGraphics.GetHdc();
   BitBlt(dc2, 0, 0, this.ClientRectangle.Width, this.ClientRectangle.Height, dc1, 0, 0, 13369376);
   mygraphics.ReleaseHdc(dc1);
   memoryGraphics.ReleaseHdc(dc2);
}
private void printDocument1_PrintPage(System.Object sender, System.Drawing.Printing.PrintPageEventArgs e) {
   e.Graphics.DrawImage(memoryImage, 0, 0);
}
private void printButton_Click(System.Object sender, System.EventArgs e) {
   CaptureScreen();
   printDocument1.Print();
}

Imprimir un archivo de texto

System.IO.StreamReader fileToPrint;
System.Drawing.Font printFont;
private void printButton_Click(object sender, EventArgs e) {
   string printPath = System.Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
   fileToPrint = new System.IO.StreamReader(printPath + @"\myFile.txt");
   printFont = new System.Drawing.Font("Arial", 10);
   printDocument1.Print();
   fileToPrint.Close();
}
 
private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e) {
   float yPos = 0f;
   int count = 0;
   float leftMargin = e.MarginBounds.Left;
   float topMargin = e.MarginBounds.Top;
   string line = null;
   float linesPerPage = e.MarginBounds.Height/printFont.GetHeight(e.Graphics);
   while (count < linesPerPage) {
      line = fileToPrint.ReadLine();
      if (line == null) {
         break;
      }
      yPos = topMargin + count * printFont.GetHeight(e.Graphics);
      e.Graphics.DrawString(line, printFont, Brushes.Black, leftMargin, yPos, new StringFormat());
      count++;
   }
   if (line != null) {
      e.HasMorePages = true;
   }
}

GDI+ y gráficos

Dar doble buffer a un formulario

this.SetStyle(ControlStyles.DoubleBuffer | ControlStyles.AllPaintingInWmPaint , true);

Dibujar texto vertical

private void DrawVerticalText() {
   System.Drawing.Graphics formGraphics = this.CreateGraphics();
   string drawString = "Sample Text";
   System.Drawing.Font drawFont = new System.Drawing.Font("Arial", 16);
   System.Drawing.SolidBrush drawBrush = new System.Drawing.SolidBrush(System.Drawing.Color.Black);
   float x = 150.0f;
   float y = 50.0f;
   System.Drawing.StringFormat drawFormat = new System.Drawing.StringFormat(StringFormatFlags.DirectionVertical);
   formGraphics.DrawString(drawString, drawFont, drawBrush, x, y, drawFormat);
   drawFont.Dispose();
   drawBrush.Dispose();
   formGraphics.Dispose();
}

Crear un buffer de una imágen

// Define a pen
System.Drawing.Pen myPen = new Pen(new SolidBrush(Color.Black));
// Obtain the form's Graphics object.
System.Drawing.Graphics formGraphics = this.CreateGraphics();
// Define the bitmap for the buffer.
Bitmap bufferBitmap = new Bitmap(this.Width, this.Height);
System.Drawing.Graphics bufferGraphics = Graphics.FromImage(bufferBitmap);
// Draw into the buffer.
for (int x = 0; x < 300; x += 2)
    bufferGraphics.DrawLine(myPen, 0, 0, x, 300);
// Copy the buffer to the form.
formGraphics.DrawImage(bufferBitmap, 0, 0);
// Clean up resources.
formGraphics.Dispose();
bufferGraphics.Dispose();

Cambiar una imágen de formato

// Load the image
Image myImage = Image.FromFile(@"C:\test.bmp");
// Save the image in JPEG format.
myImage.Save(@"C:\test.jpg",System.Drawing.Imaging.ImageFormat.Jpeg);
// Save the image in GIF format.
myImage.Save(@"C:\test.gif",System.Drawing.Imaging.ImageFormat.Gif);
// Save the image in PNG format.
myImage.Save(@"C:\test.png",System.Drawing.Imaging.ImageFormat.Png);

Crear un bitmap en tiempo de diseño

void CreateBitmap(){
    System.Drawing.Bitmap flag = new System.Drawing.Bitmap(10, 10);
    for( int x = 0; x <  flag.Height; ++x )
        for( int y = 0; y < flag.Width; ++y )
            flag.SetPixel(x, y, Color.White);
    for( int x = 0; x < flag.Height; ++x )
        flag.SetPixel(x, x, Color.Red);
    pictureBox1.Image = flag;
}

Pasar de un archivo imágen a byte[]

System.Windows.Forms.OpenFileDialog dialog = new OpenFileDialog();
if (dialog.ShowDialog() == DialogResult.OK) {
	System.IO.FileStream stream = new System.IO.FileStream(dialog.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
	byte[] buffer = new byte[stream.Length];
	stream.Read(buffer, 0, (int)stream.Length);
	stream.Close();
	this.imgInBytes = buffer;
	this.Carga();
}

Y del byte[] a un objeto Image:

if (this.imgInBytes != null) {
	System.IO.MemoryStream stream = new System.IO.MemoryStream(this.imgInBytes, true);
	this.Image = new System.Drawing.Bitmap(stream);
} else
	this.Image = null;

Pasar de un Image a byte[]

System.IO.MemoryStream ms = new System.IO.MemoryStream();
this.Image.Save(ms, this.Image.RawFormat);
byte[] buffer = ms.GetBuffer();
ms.Close();
return buffer;

Otros

Hacer sonar un beep

using System.Runtime.InteropServices;
// Declare the interop API:
[DllImport("kernel32.dll")]
public static extern bool Beep(uint dwFreq, uint dwDuration);
// Make the interop call:
if (!Beep(440, 250))
  // If the call the beep fails (if the computer has no sound card
  // for example) display a warning dialog in its place.
  MessageBox.Show("Alert.");
}

IP local y Nombre de Host

Poner en el textBox1 el nombre de host y en el 2 la IP (necesitamos incluir System.Net y System.Net.Sockets):

textBox1.Text = Dns.GetHostName();
IPAddress objIPAddress = new IPAddress(Dns.GetHostByName (Dns.GetHostName()).AddressList[2].Address);
textBox2.Text = objIPAddress.ToString();

Estamos cogiendo la 2ª IP de la máquina (AddressList[2]) podemos recorrer el array y recogerlas todas.

Mostrar una página en el IE

System.Diagnostics.Process.Start("C:\\Program Files\\Internet Explorer\\IExplore.exe", "www.microsoft.com");

Lanzar un programa a un fichero asociado

System.Diagnostics.Process.Start("c:\\test.txt");

La llamada a Process.Start requiere plena confianza de permisos en el SO (SecurityException).

Listar de Agregar y Quitar Programas mediante el uso del registro

static void Main(string[] args) {
	string clave = "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall";
	object valor = "";
	RegistryKey Reg = Registry.LocalMachine;
	Reg = Reg.OpenSubKey(clave);
	string [] SubKeyNames = Reg.GetSubKeyNames();
	foreach (string str in SubKeyNames) {
		RegistryKey tmpReg = Registry.LocalMachine;
		tmpReg = tmpReg.OpenSubKey(clave + "\\" + str);
		valor = tmpReg.GetValue("DisplayName");
		if (valor != null)
			Console.WriteLine(valor);
	}
	Console.ReadLine();
}

Recoger variables de entorno (ubicación escritorio, nombre de usuario actual…)

object s=System.Environment.GetEnvironmentVariables();
Environment.TickCount
Environtmen.SpecialFolder. ...

Saber si un ensamblado es debug o release

Assembly assm = Assembly.LoadFrom(filename);
bool found = assm.GetCustomAttributes(typeof(DebuggableAttribute), false).Length > 0;
buildType = found ? "Debug" : "Release";

Saber las fuentes instaladas en el sistema

System.Drawing.Text.InstalledFontCollection

Saber el usuario que está ejecutando el programa

Dentro de System.Security.Principal …

WindowsIdentity id = WindowsIdentity.GetCurrent();
id.name;

Lanzar un comando y quedarte con su salida

public static string Command(string command, string pars)
{
	System.Diagnostics.Process process = new System.Diagnostics.Process();
    process.StartInfo.FileName = command;
    process.StartInfo.Arguments = pars;
 
    try
    {
        process.StartInfo.CreateNoWindow = true;
        process.StartInfo.UseShellExecute = false;
        process.StartInfo.RedirectStandardOutput = true;
        process.StartInfo.WorkingDirectory = Environment.CurrentDirectory;
 
        process.Start();
        process.WaitForExit(Int32.MaxValue);
    }
    catch (Exception exc)
    {
        return exc.Message + "\n" + exc.StackTrace;
    }
 
    string ConsoleOutput = process.StandardOutput.ReadToEnd();
    return ConsoleOutput;
}

Encriptar en MD5

using System;
using System.Text;
using System.Security.Cryptography;
...
public string EncodePassword(string originalPassword)
{
  Byte[] originalBytes;
  Byte[] encodedBytes;
  MD5 md5 = new MD5CryptoServiceProvider();
  originalBytes = ASCIIEncoding.Default.GetBytes(originalPassword);
  encodedBytes = md5.ComputeHash(originalBytes);
  return BitConverter.ToString(encodedBytes);
}

… o …

System.Security.Cryptography.MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider();
byte[] bs = System.Text.Encoding.UTF8.GetBytes(text);
bs = x.ComputeHash(bs);
System.Text.StringBuilder s = new System.Text.StringBuilder();
foreach (byte b in bs)
    s.Append(b.ToString("x2").ToLower());
return s.ToString();

Aplicación en background

class Server {
    public void Start() {
        lock (this) {
            Monitor.Wait(this);
        }
    }
 
    static void Main(string[] args) {
        new Server().Start();
    }
}

Trabajar con fuentes de datos

Tipo, nombre y número de campos

SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
SqlDataReader reader = cmd.ExecuteReader();
Console.WriteLine("Column Name:\t{0} {1}", reader.GetName(0).PadRight(25), reader.GetName(1));
Console.WriteLine("Data Type:\t{0} {1}", reader.GetDataTypeName(0).PadRight(25), reader.GetDataTypeName(1));
Console.WriteLine("Number of columns in a row: {0}", reader.FieldCount);
Console.WriteLine("'{0}' is at index {1} and its type is: {2}", reader.GetName(0), reader.GetOrdinal("FirstName"), reader.GetFieldType(0));
Console.WriteLine("'{0}' is at index {1} and its type is: {2}", reader.GetName(1), reader.GetOrdinal("LastName"), reader.GetFieldType(1));
reader.Close();
conn.Close();

Acceder a una DB Access

Access, al ser datos OLEDB, necesitamos objetos de System.Data.OleDb.

System.Data.OleDb.OleDbConnection con = new System.Data.OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\"C:\\prueba.mdb\"");
con.Open();
System.Data.OleDb.OleDbCommand cmd = new System.Data.OleDb.OleDbCommand("select * from Tabla1;", con);
System.Data.OleDb.OleDbDataReader reader = cmd.ExecuteReader();
while (reader.Read())
    Console.WriteLine("Id: {0} Nombre: {1}", reader["id"], reader["nombre"]);
con.Close();

Programming

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