Programming C#, Third Edition

The foreach Statement

The foreach looping statement is new to the C family of languages, though it is already well known to VB programmers. The foreach statement allows you to iterate through all the items in an array or other collection, examining each item in turn. The syntax for the foreach statement is:

               foreach (type identifier 
               in 
               expression) statement

Thus, you might update Example 9-1 to replace the for statements that iterate over the contents of the array with foreach statements, as shown in Example 9-2.

Example 9-2. Using foreach

namespace Programming_CSharp
{
   using System;
  
   // a simple class to store in the array
   public class Employee
   {
      // a simple class to store in the array
      public Employee(int empID)
      {
         this.empID = empID;
      }
      public override string ToString( )
      {
         return empID.ToString( );
      }
      private int empID;
   }
   public class Tester
   {
      static void Main( )
      {
         int[] intArray;
         Employee[] empArray;
         intArray = new int[5];
         empArray = new Employee[3];

         // populate the array
         for (int i = 0;i<empArray.Length;i++)
         {
            empArray[i] = new Employee(i+5);
         }

         foreach (int i in intArray)
         {
             Console.WriteLine(i.ToString( ));
         } 
         foreach (Employee e in empArray)
         {
                Console.WriteLine(e.ToString( ));
         }
      }
   }
}

The output for Example 9-2 is identical to Example 9-1. However, rather than creating a for statement that measures the size of the array and uses a temporary counting variable as an index into the array as in the following, we try another approach:

for (int i = 0; i < empArray.Length; i++) { Console.WriteLine(empArray[i].ToString( ...