如何resizeC#数组长度

表示今天被一个问题困惑到了。C#中数组的Length的大小到底是数组申请内存大小还是实际存储的元素长度。我们可以

int[] a = new int[10];

a[0]=1;

a[1]=2;

a[2]=3;  //但是我只初始化前三个元素

如果在保留数组中原有的内容的基础上，怎么设置一个Resize(int[] arr, int newsize)方法，供我们调节（增大或减小）数组长度。

这样我还能用a.Length吗？

在网上找到一个resize的代码~是用Length的~ 

先记着这个问题，自己下去再试试吧~

转自http://www.source-code.biz/snippets/csharp/1.htm

How to resize an array in C#

In C#, arrays cannot be resized dynamically. One approach is to use System.Collections.ArrayListinstead of a native array. Another (faster) solution is to re-allocate the arraywith a different size and to copy the contents of the old array to the newarray. 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<a.Length; i++)      System.Console.WriteLine (a[i]); }