How to resize an array in C# (CSharp):

How to resize an array in C#

In C#, arrays cannot be resized dynamically. One approach is to use System.Collections.ArrayList instead of a native array. Another (faster) solution is to re-allocate the array with a different size and to copy the contents of the old array to the new array. The generic function resizeArray (below) can be used to do that.

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// Reallocates an array with a new size, and copies the contents
// of the old array to the new array.
// Arguments:
//   oldArray  the old array, to be reallocated.
//   newSize   the new array size.
// Returns     A new array with the same contents.
public static System.Array ResizeArray (System.Array oldArray, int newSize) {
  int oldSize = oldArray.Length;
  System.Type elementType = oldArray.GetType().GetElementType();
  System.Array newArray = System.Array.CreateInstance(elementType,newSize);
  int preserveLength = System.Math.Min(oldSize,newSize);
  if (preserveLength > 0)
     System.Array.Copy (oldArray,newArray,preserveLength);
  return newArray; }

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// Test routine for ResizeArray().
public static void Main () {
  int[] a = {1,2,3};
  a = (int[])ResizeArray(a,5);
  a[3] = 4;
  a[4] = 5;
  for (int i=0; i     System.Console.WriteLine (a[i]); }