Declaring Massive Arrays on the Stack: Is It Feasible?

When attempting to declare an array of colossal size, such as 4200000 doubles, within Dev C , users may encounter unforeseen issues. While the compiler may not flag errors, the program abruptly terminates upon execution. Moreover, this predicament arises only with arrays of substantial size, while those of smaller dimensions function impeccably.

Despite the inherent drawbacks of allocating such a large array on the stack, the unique demands of a simulation necessitate direct element access for efficient calculations. This poses a quandary: can this array be declared on the stack in a manner that circumvents the aforementioned hurdles?

The answer, unfortunately, is no. While declaring the array on the stack is not a viable option, there exists a solution that combines elements from both the stack and heap:

double *n = new double[4200000];

By using this approach, the pointer n is declared on the stack, while the memory for the array is allocated on the heap. Subsequently, accessing n[234] with this method becomes indistinguishable from accessing n[234] in an array declared as follows:

double n[500];

For enhanced performance, vectors can be employed:

std::vector someElements(4200000);
someElements[234];

Furthermore, vectors are safer and equally efficient when optimized with -O3.

With the alternative method of allocating memory dynamically:

double *n = new double[4200000];

It is crucial to deallocate the memory explicitly:

delete[] n;

Failing to do so results in memory leaks and potential instability. Therefore, this technique is inherently unsafe, especially when handling exceptions and other complexities.