I'm C/C++ to C# developer.
I need to do something like below,
#define LEN 20 int data[LEN]; Since C# doesn't support #define, many forums suggests to declare a const variable. A const variable might help me for below, but not for above.
for (int a = 0; a < LEN; a++) { x += data[LEN - a - 1]; } So, how do I use the constant for array declarations as well?
C# lets you create constants of several built-in types using const keyword.
Constants can be numbers, Boolean values, strings, or a null reference.
Here is a small example:
public class Demo { public const int Length = 20; public void Main(string[] args) { var data = new int[Length]; for (var i = 0 ; i != Length ; i++) { data[i] = 2*i + 3; } } } Note: C# naming guidelines suggest avoiding all-caps naming.
Actually you should use it for the instantiation of the array:
const int LEN = 20; int[] data = new int[LEN]; 
LEN?
you could do something like this
static readonly int LEN = 20; static void Main(string[] args) { int[] data = new int[LEN]; for (int a = 0; a < LEN; a++) { int x = data[LEN]; } } please note that that date array will be default initialized to 0.
also, you will get System.IndexOutOfRangeException for int x = data[LEN]; because you are asking for the 20th index and there is no such index in the array
You should not use constants to declare an array length. Also, there are many data structures in C# that allow you to have a dynamic size array/list/dictionary...
int x = data[LEN];doesn't declare an array-type variable, nor does it create an array - that has nothing to do with constants, it's just incorrect syntax. You could useint[] data = new int[LEN];...new[LEN]in C++. There are no arrays with automatic storage duration, as there is in C++. 2)#definedoesn't create a constant. It is merely a textual replacement, which uses find-and-replace to replace every occurence ofLENto20.int x = data[LEN];is corrected now.