Add dynamic event to controls (C#)

C# > ComponentModel > CancelEventHandler 

Delegates the method that handles a cancel event.

Example

Add dynamic event to TextBox

txtReportHeader.Validating += new CancelEventHandler(MyValidating);

private void MyValidating(object sender, CancelEventArgs e)
{
     // some validation
}

Set font bold label (C#)

C# > Drawing > Font > Bold

Bold indicates when Font is bold.

Example:

label1.Font = new System.Drawing.Font(label1.Font, FontStyle.Bold);

?: Operator (Ternary) (C#)

C# > Operators > Ternary (?:)

Ternary (conditional) operator (?:) returns one of two values depending on the value of a Boolean expression.

The syntax for the ternary operator is

condition ? first_expression : second_expression;

Example:

namespace WindowsFormsApplication1

{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private string OddOrEven(int x)
        {
            return (x % 2 == 0) ? "Number is even" : "Number is odd";
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            string s;
            s = OddOrEven(10); // Number is even
            s = OddOrEven(11); // Number is odd
        }
    }
}

Verbatim String Literals (C#)

C# > Verbatim String Literals 

In a verbatim string literal, the characters between the delimiters are interpreted verbatim, the only exception being a quote-escape-sequence.

Suppose you want to set a string as following:

string path = "C:\\Programs\\MyProgram\\My.exe";

You can use the verbatim string literal character (@) to build the string exactly as it appears within the double quotation marks.

string path = @"C:\Programs\MyProgram\My.exe";

Escape sequences (C#)

C# > Escape sequences

The special escape character is the backslash character (\).

\" Display a double quotation mark.
\'  Display a single quotation mark.
\\  Display a backslash.

\0 Null

\a Alarm

\b Backspace

\f Form feed

\n Newline

\r Carriage return

\t Tab

\v Vertical tab

  

string msg = "Dan said: \"Hello world!\"";
Result is:
Dan said: "Hello world!"

string path = "C:\\MyDir";
Result is:
C:\MyDir

Filter DataTable with LINQ (Visual Basic)

VB.NET > Data > DataTable > Filter with LINQ

Use AsEnumerable method to return the input type DataTable as IEnumerable.
The CopyToDataTable method takes the results of a query and copies the data into a DataTable.






Example:

Public Class Form1

  Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    Dim dt As DataTable = New DataTable("table")
    dt.Columns.Add("id", Type.GetType("System.Int32"))
    dt.Columns.Add("name", Type.GetType("System.String"))

    Dim dr As DataRow = dt.NewRow()

    dr("id") = 1
    dr("name") = "john"
    dt.Rows.Add(dr)

    dr = dt.NewRow()

    dr("id") = 2
    dr("name") = "dan"
    dt.Rows.Add(dr)

    Dim filteredTable As DataTable = (From n In dt.AsEnumerable()

        Where n.Field(Of Int32)("id") = 1
                    Select n).CopyToDataTable()

    ComboBox1.DataSource = filteredTable
    ComboBox1.DisplayMember = "name"
    ComboBox1.ValueMember = "id"
  End Sub

End Class

Regular expression pattern Split method in C#

C# > Text > Regular Expressions > Split

Splits an input string into an array of substrings at the positions defined by a regular expression pattern.

Example:

string path = "some_text_words";

string[] substrings = Regex.Split(path, "_");

foreach (string match in substrings)

{}