C# if...else if...else语句

using System;

namespace DecisionMaking {

   class Program {

      static voID Main(string[] args) {
         /* local variable deFinition */
         int a = 100;

         /* check the boolean condition */
         if (a == 10) {
            /* if condition is true then print the following */
            Console.Writeline("Value of a is 10");
         } else if (a == 20) {
            /* if else if condition is true */
            Console.Writeline("Value of a is 20");
         } else if (a == 30) {
            /* if else if condition is true  */
            Console.Writeline("Value of a is 30");
         } else {
            /* if none of the conditions is true */
            Console.Writeline("None of the values is matching");
         }
         Console.Writeline("Exact value of a is: {0}", a);
         Console.Readline();
      }
   }
}