Why is there an overload for String.Concat() which accepts one parameter in .NET

Question

Noticed this today when a patch was submitted with the following line:

lblCompletionTime.Text = String.Concat(trainingSkill.EndTime.ToLocalTime())

I can understand why the contributor used that syntax as above line concatenated two strings to form a multi-part date/time string.

Is there some hidden reason for having a single parameter overload of String.Concat() or was it included for "completeness" by the language designers.

I have replaced the line with:

lblCompletionTime.Text = trainingSkill.EndTime.ToLocalTime().ToString(CultureInfo.CurrentCulture)

Which has the same output.

Answer 1

According to MSDN, String.Concat(object)

Creates the String representation of a specified object.

Answer 2

String.Concat(Object) gives you String.Empty when you pass null; ToString would crash with a null pointer exception.

Answer 3

I agree that it doesn't make much sense especially considering the fact that this is the implementation:

public static string Concat(object arg0)
{
        if (arg0 == null)
        {
                return Empty;
        }
        return arg0.ToString();
}

But it does validate that the argument isn't null so I guess that is something. Still you aren't concatenating anything so I think that this method could have been called

String.ToStringSafe(Object obj) { }

or something similar to better express what the function actually does.

Answer 4

Using String.Concat(Object) to convert an object to a string is the behavior that overload of the function was designed for.

String.Concat Method (Object)
Creates the String representation of a specified object.

Answer 5

By looking at the documentation of String.Concat(object), the only advantage I see is that it accepts a null and returns an empty string, which can be an advantage when compared with object.ToString() which would throw a NullReferenceException. In your example it doesn't help because if trainingSkill.EndTime is null the program will break when invoking ToLocalTime. I preffer your correction, but I think there's no need for passing CultureInfo.CurrentCulture as a parameter since it is the default behaviour of DateTime.ToString()

Answer 6

In C# it may have little value (aside from the automatic empty string for a null value).

In .Net in general, I could this method signature being very useful in a functional language.