A string that consists of the elements of values delimited by the separator string. If values is an empty array, the method returns string.Empty.
If separator is null or if any element of values other than the first element is null, an empty string (string.Empty) is used instead. See the Notes for Callers section if the first element of values is null.
string.Join(string, Object) is a convenience method that lets you concatenate each element in an object array without explicitly converting its elements to strings. The string representation of each object in the array is derived by calling that object's ToString method.