Why doesn't object have an overload that accepts IFormatProvider?

Question

When converting for instance a decimal to a string, you use the CultureInfo.InvariantCulture and pass it as an IFormatProvider

Answer 1

Handy extension method of Peter's solution (modified to test also for IConvertible).

public static string ToInvariantString(this object obj)
{
    return obj is IConvertible ? ((IConvertible)obj).ToString(CultureInfo.InvariantCulture)
        : obj is IFormattable ? ((IFormattable)obj).ToString(null, CultureInfo.InvariantCulture)
        : obj.ToString();
}