Why does Activator.CreateInstance take a CultureInfo argument?

Question

Activator.CreateInstance takes a CultureInfo argument. The docs give the following description for this argument:

Culture-specific information that governs the coercion of args to the formal types declared for the type constructor. If culture is null, the CultureInfo for the current thread is used.

What does this mean? What are some examples of when one culture would give a different result than a different culture?

Answer 1

The CultureInfo argument in Activator.CreateInstance is used when converting constructor arguments to the required types, particularly for parsing culture-sensitive data like numbers and dates.

As an example: Different number format. Some cultures use a comma (,) as a decimal separator, while others use a period (.). This can affect how numbers are parsed when passed as constructor arguments.

using System;
using System.Globalization;

public class Example
{
    public double Value { get; }

    public Example(double value)
    {
        Value = value;
    }
}

class Program
{
    static void Main()
    {
        object[] args = { "3,14" }; // String representation of a number

        // Using German culture (comma as decimal separator)
        var germanCulture = new CultureInfo("de-DE");
        var instanceDE = (Example)Activator.CreateInstance(typeof(Example), args, null, germanCulture, null);
        Console.WriteLine(instanceDE.Value); // Output: 3.14

        // Using US culture (period as decimal separator)
        var usCulture = new CultureInfo("en-US");
        var instanceUS = (Example)Activator.CreateInstance(typeof(Example), args, null, usCulture, null);
        Console.WriteLine(instanceUS.Value); // Throws exception (cannot parse "3,14" as a double)
    }
}