Thursday, 31 March 2016

What is the difference between methods – “System.Array.Clone()” and “System.Array.CopyTo()” in C#?

  • “CopyTo()” method can be used to copy the elements of one array to other. 
  • “Clone()” method is used to create a new array to contain all the elements which are in the original array.
using System;
using System.Globalization;
public class SamplesArray  {

   public static void Main()  {

      // Create and initialize a new CultureInfo array.
      CultureInfo ci0 = new CultureInfo( "ar-SA", false );
      CultureInfo ci1 = new CultureInfo( "en-US", false );
      CultureInfo ci2 = new CultureInfo( "fr-FR", false );
      CultureInfo ci3 = new CultureInfo( "ja-JP", false );
      CultureInfo[] arrCI = new CultureInfo[] { ci0, ci1, ci2, ci3 };

      // Create a clone of the CultureInfo array.
      CultureInfo[] arrCIClone = (CultureInfo[]) arrCI.Clone();

      // Replace an element in the clone array.
      CultureInfo ci4 = new CultureInfo( "th-TH", false );
      arrCIClone[0] = ci4;

      // Display the contents of the original array.
      Console.WriteLine( "The original array contains the following values:" );
      PrintIndexAndValues( arrCI );

      // Display the contents of the clone array.
      Console.WriteLine( "The clone array contains the following values:" );
      PrintIndexAndValues( arrCIClone );

      // Display the DateTimeFormatInfo.DateSeparator for the fourth element in both arrays.
      Console.WriteLine( "Before changes to the clone:" );
      Console.WriteLine( "   Original: The DateTimeFormatInfo.DateSeparator for {0} is {1}.", arrCI[3].Name, arrCI[3].DateTimeFormat.DateSeparator );
      Console.WriteLine( "      Clone: The DateTimeFormatInfo.DateSeparator for {0} is {1}.", arrCIClone[3].Name, arrCIClone[3].DateTimeFormat.DateSeparator );

      // Replace the DateTimeFormatInfo.DateSeparator for the fourth element in the clone array.
      arrCIClone[3].DateTimeFormat.DateSeparator = "-";

      // Display the DateTimeFormatInfo.DateSeparator for the fourth element in both arrays.
      Console.WriteLine( "After changes to the clone:" );
      Console.WriteLine( "   Original: The DateTimeFormatInfo.DateSeparator for {0} is {1}.", arrCI[3].Name, arrCI[3].DateTimeFormat.DateSeparator );
      Console.WriteLine( "      Clone: The DateTimeFormatInfo.DateSeparator for {0} is {1}.", arrCIClone[3].Name, arrCIClone[3].DateTimeFormat.DateSeparator );

   }

   public static void PrintIndexAndValues( Array myArray )  {
      for ( int i = myArray.GetLowerBound(0); i <= myArray.GetUpperBound(0); i++ )
         Console.WriteLine( "\t[{0}]:\t{1}", i, myArray.GetValue( i ) );
   }

}


/* 
This code produces the following output.

The original array contains the following values:
        [0]:    ar-SA
        [1]:    en-US
        [2]:    fr-FR
        [3]:    ja-JP
The clone array contains the following values:
        [0]:    th-TH
        [1]:    en-US
        [2]:    fr-FR
        [3]:    ja-JP
Before changes to the clone:
   Original: The DateTimeFormatInfo.DateSeparator for ja-JP is /.
      Clone: The DateTimeFormatInfo.DateSeparator for ja-JP is /.
After changes to the clone:
   Original: The DateTimeFormatInfo.DateSeparator for ja-JP is -.
      Clone: The DateTimeFormatInfo.DateSeparator for ja-JP is -.

*/







object[] myarray = new object[] { "one", 2, "three", 4, "really big number", 2324573984927361 };

//create shallow copy by CopyTo
//You have to instantiate your new array first
object[] myarray2 = new object[myarray.Length];
//but then you can specify how many members of original array you would like to copy 
myarray.CopyTo(myarray2, 0);

//create shallow copy by Clone
object[] myarray1;
//here you don't need to instantiate array, 
//but all elements of the original array will be copied
myarray1 = myarray.Clone() as object[];

//if not sure that we create a shalow copy lets test it
myarray[0] = 0;
Console.WriteLine(myarray[0]);// print 0
Console.WriteLine(myarray1[0]);//print "one"
Console.WriteLine(myarray2[0]);//print "one"

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