访问修饰符 class 类名 
 { 
 //类成员：
 // Methods, properties, fields, events, delegates 
 // and nested classes go here. 
 }

class Child
 {
 private int age;
 private string name;
 // Default constructor:
 public Child()
 {
 name = "Lee";
 }
 // Constructor:
 public Child(string name, int age)
 {
 this.name = name;
 this.age = age;
 }
 // Printing method:
 public void PrintChild()
 {
 Console.WriteLine("{0}, {1} years old.", name, age);
 }
 }
 class StringTest
 {
 static void Main()
 {
 // Create objects by using the new operator:
 Child child1 = new Child("Craig", 11);
 Child child2 = new Child("Sally", 10);
 // Create an object using the default constructor:
 Child child3 = new Child();
 // Display results:
 Console.Write("Child #1: ");
 child1.PrintChild();
 Console.Write("Child #2: ");
 child2.PrintChild();
 Console.Write("Child #3: ");
 child3.PrintChild();
 }
 }
 /* Output:
 Child #1: Craig, 11 years old.
 Child #2: Sally, 10 years old.
 Child #3: N/A, 0 years old.
 */