More About Classes - Illustrated C# 2005 - page 120

Default Constructors
If no instance constructor is explicitly supplied in the class declaration, then the compiler sup-
plies an implicit, default constructor with

￿ No parameters

￿ An empty body

If the programmer defines any constructor at all, then the compiler does not define any
default constructors for the class.
For example, Class2 declares two constructors.

￿ Because there is at least one explicitly defined constructor, the compiler does not create

any additional constructors.

￿In Main , there is an attempt to create a new instance using a constructor with no param-
eters. Since there is no constructor with zero parameters, the compiler will produce an
error message.

class Class2
{
public Class2(int Value) { ... } // Constructor 0
public Class2(String Value) { ... } // Constructor 1
}

class Program
{
static void Main()
{
Class2 a = new Class2(); // Error! No constructor with 0 parameters
...
}
}