HOW to check the presence of array[3][4] element in D or d C++?

Question

C++ / C#

HOW to check the presence of an element in a byte[int][int] array in D or d C++?
And then a Range error pops up

Answer 1

Depending on what "the presence of an element in an array" means. If the array is static, then the element is always there. And if it is dynamic, then in D you can check that such indexes exist, like this for example:

auto array = new int[10][20];

/* ... */

writeln(array.length);  // напишет 20
writeln(array[0].length); // напишет 10

// проверим, что есть элемент [3][4]
if ((array.length < 4) || (array[0].length < 3))
  writeln("fail"); // а вот это не напишет, значит элемент [3][4] доступен.

You can also explicitly catch an exception when a non-existent element is read:

auto array = new int[10][20];

/* ... */

bool isElementExist(int[10][] a, size_t indexA, size_t indexB)
{
  try { auto i = a[indexA][indexB]; }
  catch { return false; }
  return true;
}

/* ... */

writeln(isElementExist(array, 300, 4)); // false
writeln(isElementExist(array, 3, 4)); // true

Answer 2

In D, no idea, in C ++, in principle, in no way. Only if you use containers.
And if C and C++ are different programming languages, then D has nothing to do with them at all.