Tim Van Wassenhove

Passionate geek, interested in Technology. Proud father of two

28 Jul 2007

Exploring formatting...

In the documentation you can read the following for CultureInfo

First i’ll initialize an instance of a customized CultureInfo and install it in the current thread:

CultureInfo appCultureInfo = new CultureInfo("en-US");
appCultureInfo.NumberFormat.NumberDecimalSeparator = ".";
appCultureInfo.NumberFormat.NumberGroupSeparator = " ";
appCultureInfo.NumberFormat.NumberDecimalDigits = 2;
appCultureInfo.NumberFormat.CurrencySymbol = "€";
Thread.CurrentThread.CurrentCulture = appCultureInfo;

Note: The culture in Thread.CurrentThread.CurrentUICulture is only used by the Resource Manager to lookup culture-specific resources at run-time. Since we’re not playing with resources, we don’t have to care about this one.

If you don’t provide the desired format specifier, you will get the generic format specifier “G” ( Standard Numeric, DateTime, Enumeration Format Strings) And now it’s time for a little demo

public double SomeValue
	get { return 12345.6789; }

private void Form1_Load(object sender, EventArgs e)
	label1.Text = "default to generic format: " + SomeValue.ToString();
	label2.Text = "numeric format: " + SomeValue.ToString("N");
	label3.Text = String.Format("currency format: {0:C}", SomeValue);
	label4.DataBindings.Add("Text", this, "SomeValue", true, DataSourceUpdateMode.Never, string.Empty, "P");

	this.Column1.DefaultCellStyle.Format = "E1";
	this.Column1.DataPropertyName = "SomeValue";
	this.dataGridView1.AutoGenerateColumns = false;
	this.dataGridView1.DataSource = new Form1[] { this };

Another important interface for formatting is IFormattable which provides functionality to format the value of an object into a string representation. Put simply, it allows you to define your own format specifiers. Here is an example that allows the user to build his own representation of a Person

class Person : IFormattable
	// omitted the code for 4 properties: Id, Name, Title and Birthday

	public override string ToString()
		return ToString("{Id}, {Name}", null);

	public string ToString(string format, IFormatProvider formatProvider)
		string actualFormat = format;

		string[] replacements = new string[] { "Id", "Name", "Title", "Birthday" };
		for (int i = 0; i < replacements.Length; ++i) 
			actualFormat = actualFormat.Replace(replacements[i], i.ToString()); 
		return string.Format(actualFormat, this.id, this.name, this.title, this.birthday); 

private void Form1_Load(object sender, EventArgs e) 
	List<person> persons = new List<person>();
	persons.Add(new Person(1, new DateTime(1980, 4, 30), "Tim", "Sir"));
	persons.Add(new Person(2, new DateTime(1974, 4, 9), "Jenna", "Miss"));

	this.comboBox1.FormatString = "{Name} born on {Birthday}";
	this.comboBox1.FormattingEnabled = true;
	this.comboBox1.DataSource = persons;