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Is it possible to change an array size after declaration? If not, is there any alternative to arrays? I do not want to create an array with a size of 1000, but I do not know the size of the array when I'm creating it.

No, try using a strongly typed List instead.

For example:

Instead of using

int[] myArray = new int[2];
myArray[0] = 1;
myArray[1] = 2;

You could do this:

List<int> myList = new List<int>();
myList.Add(1);
myList.Add(2);

Lists use arrays to store the data so you get the speed benefit of arrays with the convenience of a LinkedList by being able to add and remove items without worrying about having to manually change its size.

This doesn't mean an array's size (in this instance, a List) isn't changed though - hence the emphasis on the word manually.

As soon as your array hits its predefined size, the JIT will allocate a new array on the heap that is twice the size and copy your existing array across.

change array size, No, try using a strongly typed List instead. For example: Instead of using int[] myArray = new int[2]; myArray[0] = 1; myArray[1] = 2;. You could do  Once an array is created, its size cannot be changed. If you want to change the size, you must create a new array and populates it using the values of the old array.

You can use Array.Resize(), documented in MSDN.

But yeah, I agree with Corey, if you need a dynamically sized data structure, we have Lists for that.

Important: Array.Resize() doesn't resize the array (the method name is misleading), it creates a new array and only replaces the reference you passed to the method.

An example:

var array1 = new byte[10];
var array2 = array1;
Array.Resize<byte>(ref array1, 20);

// Now:
// array1.Length is 20
// array2.Length is 10
// Two different arrays.

Can you change size of Array in Java once created?, An array is a data structure/container/object that stores a fixed-size sequential collection of elements of the same type. The size/length of the  array = new int[someSize]; How do I do this in C++? Share a link to this question. improve this question. edited Oct 3 '10 at 19:24. 224 silver badges. 407 bronze badges. asked Oct 3 '10 at 19:07. 140 silver badges. 183 bronze badges. Do you just not know the size yet or do you know the size only after you read something at runtime? I.e. is the

You can use Array.Resize() in .net 3.5 and higher. This method allocates a new array with the specified size, copies elements from the old array to the new one, and then replaces the old array with the new one. (So you will need the memory available for both arrays as this probably uses Array.Copy under the covers)

Changing Array Size : Array Basics « Collections « Java Tutorial, Once an array is created, its size cannot be changed. If you want to change the size, you must create a new array and populates it using the values of the old  So: We reduce the size of the array by 2 elements. Array.Resize can expand, or shrink an array's size. Array.Resize can expand, or shrink an array's size. C# program that uses Array.Resize using System; class Program { static void Main() { // Step 1: initialize array for example.

Used this approach for array of bytes:

Initially:

byte[] bytes = new byte[0];

Whenever required (Need to provide original length for extending):

Array.Resize<byte>(ref bytes, bytes.Length + requiredSize);

Reset:

Array.Resize<byte>(ref bytes, 0);

Typed List Method

Initially:

List<byte> bytes = new List<byte>();

Whenever required:

bytes.AddRange(new byte[length]);

Release/Clear:

bytes.Clear()

Array.Resize<T>(T[], Int32) Method, Changing Array Size. 4.7.1. Problem. You want to modify the size of an array, either by making it larger or smaller than its current  Instead, it creates a new array of the required size. – Loul G. Mar 18 '15 at 20:58. List<Int> is using Array.Resize under the covers. It uses a generally (though not universally) optimal algorithm under the covers, wherein it doubles the size of the array each time that it grows it.

Use System.Collections.Generic.List

Changing Array Size (PHP Cookbook), This call changes an array of 4 elements to one with 2 elements. So: We reduce the size of the array by 2 elements. Array.Resize can expand, or shrink an array's​  If your array will be changing sizes often, especially as it sounds like you're just appending, you should probably use a generic List(Of T) or similar collection type. You can use it just like you use an array, with the addition that adding an item to the end is as easy as MyList.Add(item)

C# Array.Resize Examples, Or in other words, this method is used to change the number of elements of a one​-dimensional array to the specified new size. It resizes the only 1-D array, not  You're trying to edit an array formula, and you're stopped in your tracks. You click the formula in the cell or formula bar and you can't change a thing. Array formulas are a special case, so do one of the following: If you've entered a single-cell array formula, select the cell, press F2, make your changes, and then press Ctrl+Shift+Enter..

C#| How to change the size of one-dimensional array, Changing Array Size Problem You want to enlarge or truncate an array. For example, you might truncate an array of employees that's already sorted by salary to  If the size of your array increases and you don't want to fix the size of the array, you can use the ReDim keyword. Excel VBA then changes the size of the array automatically. Add some numbers to column A. Place a command button on your worksheet and add the following code lines:

Changing Array Size - Perl Cookbook [Book], We can't really resize arrays in C++, but we can do the next best thing: create a new array of a For that we need to modify the constructor function: c points to the beginning of an array of char values; the initial size, INITIAL_LENGTH , would​  The reshape function changes the size and shape of an array. For example, reshape a 3-by-4 matrix to a 2-by-6 matrix. For example, reshape a 3-by-4 matrix to a 2-by-6 matrix. A = [1 4 7 10; 2 5 8 11; 3 6 9 12]

Comments
  • Yes by this way: string[] arr1 = new string[]{}; Array.Resize(ref arr1, 7);
  • If Array.Resize() is just once at the beginning (and not multiple times during the program), is that more suitable than a List?
  • List<T> uses an Array behind the scenes, so there are very few reasons to use an Array in C#. Lists can be initialized to a suitable size using this constructor: msdn.microsoft.com/en-us/library/dw8e0z9z.aspx. But yes, if your heart is set on Arrays, it's better to resize them as infrequently as possible.
  • I thought List<T> uses a linked list or some data structure behind. So it uses array after all.
  • Be carefull, Array.Resize does not preserve your reference. Instead, it creates a new array of the required size.
  • List<Int> is using Array.Resize under the covers. It uses a generally (though not universally) optimal algorithm under the covers, wherein it doubles the size of the array each time that it grows it. Unless you are working on high performance realtime systems (high-speed trading or mechanical control systems for example) you should use List<Int> as it will be "good enough" and is more maintainable.
  • You should have commented, this post is not an answer!
  • I can only see add comment on my own post for some reason
  • The reason is that your reputation is to low.
  • What do you do by doing UpperBound?