C#中用foreach语句遍历数组及将数组作为参数的用法

int[] numbers = { 4, 5, 6, 1, 2, 3, -2, -1, 0 };
foreach (int i in numbers)
{
  System.Console.Write("{0} ", i);
}
// Output: 4 5 6 1 2 3 -2 -1 0

int[,] numbers2D = new int[3, 2] { { 9, 99 }, { 3, 33 }, { 5, 55 } };
// Or use the short form:
// int[,] numbers2D = { { 9, 99 }, { 3, 33 }, { 5, 55 } };

foreach (int i in numbers2D)
{
  System.Console.Write("{0} ", i);
}

9 99 3 33 5 55

int[] theArray = { 1, 3, 5, 7, 9 };
PrintArray(theArray);

void PrintArray(int[] arr)
{
  // Method code.
}

PrintArray(new int[] { 1, 3, 5, 7, 9 });

class ArrayClass
{
  static void PrintArray(string[] arr)
  {
    for (int i = 0; i < arr.Length; i++)
    {
      System.Console.Write(arr[i] + "{0}", i < arr.Length - 1 ? " " : "");
    }
    System.Console.WriteLine();
  }

  static void ChangeArray(string[] arr)
  {
    // The following attempt to reverse the array does not persist when
    // the method returns, because arr is a value parameter.
    arr = (arr.Reverse()).ToArray();
    // The following statement displays Sat as the first element in the array.
    System.Console.WriteLine("arr[0] is {0} in ChangeArray.", arr[0]);
  }

  static void ChangeArrayElements(string[] arr)
  {
    // The following assignments change the value of individual array 
    // elements. 
    arr[0] = "Sat";
    arr[1] = "Fri";
    arr[2] = "Thu";
    // The following statement again displays Sat as the first element
    // in the array arr, inside the called method.
    System.Console.WriteLine("arr[0] is {0} in ChangeArrayElements.", arr[0]);
  }

  static void Main()
  {
    // Declare and initialize an array.
    string[] weekDays = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };

    // Pass the array as an argument to PrintArray.
    PrintArray(weekDays);

    // ChangeArray tries to change the array by assigning something new
    // to the array in the method. 
    ChangeArray(weekDays);

    // Print the array again, to verify that it has not been changed.
    System.Console.WriteLine("Array weekDays after the call to ChangeArray:");
    PrintArray(weekDays);
    System.Console.WriteLine();

    // ChangeArrayElements assigns new values to individual array
    // elements.
    ChangeArrayElements(weekDays);

    // The changes to individual elements persist after the method returns.
    // Print the array, to verify that it has been changed.
    System.Console.WriteLine("Array weekDays after the call to ChangeArrayElements:");
    PrintArray(weekDays);
  }
}

Sun Mon Tue Wed Thu Fri Sat
arr[0] is Sat in ChangeArray.
Array weekDays after the call to ChangeArray:
Sun Mon Tue Wed Thu Fri Sat

arr[0] is Sat in ChangeArrayElements.
Array weekDays after the call to ChangeArrayElements:
Sat Fri Thu Wed Thu Fri Sat

int[,] theArray = { { 1, 2 }, { 2, 3 }, { 3, 4 } };
Print2DArray(theArray);

void Print2DArray(int[,] arr)
{
  // Method code.
}

Print2DArray(new int[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } });

class ArrayClass2D
{
  static void Print2DArray(int[,] arr)
  {
    // Display the array elements.
    for (int i = 0; i < arr.GetLength(0); i++)
    {
      for (int j = 0; j < arr.GetLength(1); j++)
      {
        System.Console.WriteLine("Element({0},{1})={2}", i, j, arr[i, j]);
      }
    }
  }
  static void Main()
  {
    // Pass the array as an argument.
    Print2DArray(new int[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } });

    // Keep the console window open in debug mode.
    System.Console.WriteLine("Press any key to exit.");
    System.Console.ReadKey();
  }
}

Element(0,0)=1
Element(0,1)=2
Element(1,0)=3
Element(1,1)=4
Element(2,0)=5
Element(2,1)=6
Element(3,0)=7
Element(3,1)=8