Mega Code Archive
0288 Custom format and a format provider
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format and format provider are linked by IFormattable interface.
All numeric types and DateTime DateTimeOffset implement this interface:
public interface IFormattable
{
string ToString (string format, IFormatProvider formatProvider);
}
The first argument is the format string.
The second is the format provider.
The format string provides instructions.
The format provider does the format based on the instructions.
using System;
using System.Text;
using System.Globalization;
class Sample
{
public static void Main()
{
NumberFormatInfo f = new NumberFormatInfo();
f.CurrencySymbol = "$$";
Console.WriteLine(3.ToString("C", f)); // $$ 3.00
}
}
The output:
$$3.00
"C" is a format string
NumberFormatInfo object is a format provider.
If you specify a null format string or provider, a default is applied
The default format provider is CultureInfo.CurrentCulture.
using System;
using System.Text;
using System.Globalization;
class Sample
{
public static void Main()
{
Console.WriteLine(10.3.ToString("C", null));
}
}
The output:
$10.30
Most types overload ToString such that you can omit the null provider
using System;
using System.Text;
using System.Globalization;
class Sample
{
public static void Main()
{
Console.WriteLine(10.3.ToString("C"));
Console.WriteLine(10.3.ToString("F4"));
}
}
The output:
$10.30
10.3000
The .NET Framework defines three format providers:
NumberFormatInfo
DateTimeFormatInfo
CultureInfo
CultureInfo is a proxy for the other two format providers.
It returns a NumberFormatInfo or DateTimeFormatInfo object applicable to the culture's regional settings.
using System;
using System.Text;
using System.Globalization;
class Sample
{
public static void Main()
{
CultureInfo uk = CultureInfo.GetCultureInfo("en-GB");
Console.WriteLine(3.ToString("C", uk));
}
}
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