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How to make the array size a ReadLine?

I'm trying to make a sorting algorithm and asking the user to input the array size is a must. I am a beginner in C# so I don't have any idea how to do that.
This is the idea that came to my mind, but I'm having an error.
Console.WriteLine("Enter how many elements you want to be sorted:");
a = Convert.ToInt32(Console.ReadLine());
int[] MyArray= new int[a] {""};
Visual Studio says that 'a constant value is expected'. How could I make the array length a ReadLine? My goal is for the user to decide which array length they want the program to show and that the elements inside the array would be system generated based on the array length that the user chose.

You can initialise an array like this:
int[] MyArray= new int[a];
But, I would also point out, that you could use a dynamic collection (such as a list), then you don't need to ask up front how many items, you just keep adding items until the user decides to stop.
ICollection<int> myCollection = new List<int>();
myCollection.Add(1);
myCollection.Add(1);

The type of your array is int but you are trying to initialize it with an empty string. In C# you can declare an array in a few ways. You can declare it by providing a size as in:
int[] myArray = new int[size];
And initialize the values later.
An alternative is to instantly intialize it with values like this:
int[] myArray = new int[] { 1, 2, 3 };
Note that when using the second option, you shouldn't provied the size as the compiler will infere it.

Storing lots of Arrays into a List on every Loop

I have a question about storing lots of arrays into a list.
First, I initialize the array and list:
int[] arr = new int[9];
List<int[]> forkarr = new List<int[]>();
then I run through a lot of for loops and modify the array each time in order to produce all possible tic tac toe variations. While looping through all those variations, if the array is a possible board then I print it, and additionally if the array meets certain criteria for being a 'fork', then I will add it to the list like this:
if (ForkCheck.fork(arr)) { forkarr.Add(arr); Console.WriteLine("It's a Fork!");}
which also prints that message letting you know that particular array is a fork.
Now, when I am printing all of the arrays, the ones that are forks are printed properly and labeled as such.
However, when I go to print out all of the int[] elements of my list forkarr like so:
foreach (int[] arry in forkarr)
{
PrintGame.print(arry);//this is my method that prints the array
Console.WriteLine();
}
for some reason each array becomes an identical:
222
222
222
(I'm using 2 as 'X' and 1 as 'O' and 0 as 'empty' btw)
And it just prints that out over and over for all the forks.
So, something is going wrong when I am adding each modification of the array as a new element in the list I think, but I'm not sure why.
Thanks for any help.

Because you are modifying the same array and adding it to the list. Each time you done with one array array you need to create a new instance like this:
arr = new int[9];
This will create a new reference which will be independent from other arrays. And modifying it's elements wont affect the others.
For more information about value vs reference types you can refer to the question below:
What is the difference between a reference type and value type in c#?

Start Index Of Multidimensional Array [duplicate]

Is it possible in c# to initialize an array in, for example, subindex 1?
I'm working with Office interop, and every property is an object array that starts in 1 (I assume it was originally programed in VB.NET), and you cannot modify it, you have to set the entire array for it to accept the changes.
As a workaround I am cloning the original array, modifying that one, and setting it as a whole when I'm done.
But, I was wondering if it was possible to create a new non-zero based array

It is possible to do as you request see the code below.
// Construct an array containing ints that has a length of 10 and a lower bound of 1
Array lowerBoundArray = Array.CreateInstance(typeof(int), new int[1] { 10 }, new int[1] { 1 });
// insert 1 into position 1
lowerBoundArray.SetValue(1, 1);
//insert 2 into position 2
lowerBoundArray.SetValue(2, 2);
// IndexOutOfRangeException the lower bound of the array
// is 1 and we are attempting to write into 0
lowerBoundArray.SetValue(1, 0);

You can use Array.CreateInstance.
See Array Types in .NET

Not simply. But you can certainly write your own class. It would have an array as a private variable, and the user would think his array starts at 1, but really it starts at zero and you're subtracting 1 from all of his array accesses.

You can write your own array class

I don't think if it's possible to modify the starting index of arrays.
I would create my own array using generics and handle it inside.

Just keep of const int named 'offset' with a value of one, and always add that to your subscripts in your code.

I don't think you can create non-zero based arrays in C#, but you could easily write a wrapper class of your own around the built in data structures.This wrapper class would hold a private instance of the array type you required; overloading the [] indexing operator is not allowed, but you can add an indexer to a class to make it behave like an indexable array, see here. The index function you write could then add (or subtract) 1, to all index's passed in.
You could then use your object as follows, and it would behave correctly:
myArrayObject[1]; //would return the zeroth element.

In VB6 you could change the array to start with 0 or 1, so I think VBScript can do the same. For C#, it's not possible but you can simply add NULL value in the first [0] and start real value at [1]. Of course, this is a little dangerous...

How to get number of elements in an array, Extension Method Count() and Length gives the size of Array.

Hi I was trying to find the number of elements in an array
byte[] salt = new byte[32];
now I only have mentioned size 32 so the Length Property of Array and Enumerable's Count Method will give me 32.
Even if I will iterate on this Array salt using for or foreach or any other looping construct it will iterate 32 times and on each index the value is 0 (i.e default value of byte)
Now suppose I do:
for (int i = 0; i < 5 ; i++)
{
salt[i] = 4-i;
}
And I want to know how many elements are inserted sequentially in Array starting from index 0, Here you may say are you fool you iterating it 5 times and you know the number is 5 , but I am having heavy looping and other logic (appending prepending to another arrays of byte) in it. *My question Is there any other inbuilt function that could give me this number 5 ? * Even if I iterate and check for first default value and break the loop there and get the count but there might be the chance last value inserted is 0 like above salt[4] is 0 so that iterating will give me the count 4 which is incorrect . If I am not wrong I think when we declare Array with size like 32 above 32 consecutive memory bytes are reserved and you are free to insert at any index from 0-31 and its your responsibility to keep the track where and how and how many elements are assigned to Array .I hope you got my point And thanks in advance for help.

An array is an array, and in .NET is initialized when it is allocated. Once it's initialized, the question of whether a given value is uninitialized or simply 0 isn't something that's possible to check. A 0 is a 0.
However, you can bypass that in several ways. You can use a List<int>, like #SLaks suggested, to have a dynamically allocated list that's only initialized with the elements you want.
You can also use, instead of an array of int, and array of int?, so a null value isn't the same as a 0.

Short answer is you can't, the array contains 32 integers, .net framework doesn't care if some of them are 0, so you can create your own function that counts how many integers from an array are different than 0, or keep a "count" when you assign values for array elements or something like that.
Or you can use another container, example a list and dynamically add or remove integers from it.

Ok, when you define an array as int[] myArray = int[32]; you are saying, I HAVE 32 ints. Not, create me space for 32 ints that I will fill in later. That's why count is giving you 32.
If you want something which you can genuinly add to and resize, you need to use a List (or one of it's relatives.
If you want to have a "cap" for a list, I found this :Maximum capacity collection in c#

Initializing an array on arbitrary starting index in c#

Is it possible in c# to initialize an array in, for example, subindex 1?
I'm working with Office interop, and every property is an object array that starts in 1 (I assume it was originally programed in VB.NET), and you cannot modify it, you have to set the entire array for it to accept the changes.
As a workaround I am cloning the original array, modifying that one, and setting it as a whole when I'm done.
But, I was wondering if it was possible to create a new non-zero based array

It is possible to do as you request see the code below.
// Construct an array containing ints that has a length of 10 and a lower bound of 1
Array lowerBoundArray = Array.CreateInstance(typeof(int), new int[1] { 10 }, new int[1] { 1 });
// insert 1 into position 1
lowerBoundArray.SetValue(1, 1);
//insert 2 into position 2
lowerBoundArray.SetValue(2, 2);
// IndexOutOfRangeException the lower bound of the array
// is 1 and we are attempting to write into 0
lowerBoundArray.SetValue(1, 0);

You can use Array.CreateInstance.
See Array Types in .NET

Not simply. But you can certainly write your own class. It would have an array as a private variable, and the user would think his array starts at 1, but really it starts at zero and you're subtracting 1 from all of his array accesses.

You can write your own array class

I don't think if it's possible to modify the starting index of arrays.
I would create my own array using generics and handle it inside.

Just keep of const int named 'offset' with a value of one, and always add that to your subscripts in your code.

I don't think you can create non-zero based arrays in C#, but you could easily write a wrapper class of your own around the built in data structures.This wrapper class would hold a private instance of the array type you required; overloading the [] indexing operator is not allowed, but you can add an indexer to a class to make it behave like an indexable array, see here. The index function you write could then add (or subtract) 1, to all index's passed in.
You could then use your object as follows, and it would behave correctly:
myArrayObject[1]; //would return the zeroth element.

In VB6 you could change the array to start with 0 or 1, so I think VBScript can do the same. For C#, it's not possible but you can simply add NULL value in the first [0] and start real value at [1]. Of course, this is a little dangerous...