Tutorial :Copy one string array to another


How can I copy a string[] from another string[]?

Suppose I have string[] args. How can I copy it to another array string[] args1?


Allocate space for the target array, that use Array.CopyTo():

targetArray = new string[sourceArray.Length];  sourceArray.CopyTo( targetArray, 0 );  


  • To create a completely new array with the same contents (as a shallow copy): call Array.Clone and just cast the result.
  • To copy a portion of a string array into another string array: call Array.Copy or Array.CopyTo

For example:

using System;    class Test  {      static void Main(string[] args)      {          // Clone the whole array          string[] args2 = (string[]) args.Clone();            // Copy the five elements with indexes 2-6          // from args into args3, stating from          // index 2 of args3.          string[] args3 = new string[5];          Array.Copy(args, 2, args3, 0, 5);            // Copy whole of args into args4, starting from          // index 2 (of args4)          string[] args4 = new string[args.Length+2];          args.CopyTo(args4, 2);      }  }  

Assuming we start off with args = { "a", "b", "c", "d", "e", "f", "g", "h" } the results are:

args2 = { "a", "b", "c", "d", "e", "f", "g", "h" }  args3 = { "c", "d", "e", "f", "g" }  args4 = { null, null, "a", "b", "c", "d", "e", "f", "g", "h" }   


The above answers show a shallow clone; so I thought I add a deep clone example using serialization; of course a deep clone can also be done by looping through the original array and copy each element into a brand new array.

 private static T[] ArrayDeepCopy<T>(T[] source)          {              using (var ms = new MemoryStream())              {                  var bf = new BinaryFormatter{Context = new StreamingContext(StreamingContextStates.Clone)};                  bf.Serialize(ms, source);                  ms.Position = 0;                  return (T[]) bf.Deserialize(ms);              }          }  

Testing the deep clone:

 private static void ArrayDeepCloneTest()          {              //a testing array              CultureInfo[] secTestArray = { new CultureInfo("en-US", false), new CultureInfo("fr-FR") };                //deep clone              var secCloneArray = ArrayDeepCopy(secTestArray);                //print out the cloned array              Array.ForEach(secCloneArray, x => Console.WriteLine(x.DateTimeFormat.DateSeparator));                //modify the original array              secTestArray[0].DateTimeFormat.DateSeparator = "-";                Console.WriteLine();              //show the (deep) cloned array unchanged whereas a shallow clone would reflect the change...              Array.ForEach(secCloneArray, x => Console.WriteLine(x.DateTimeFormat.DateSeparator));          }  

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