Array of size defined by not constant variable

Question

There is such code:

#include 

int main()
{
  int size;
  std::cin >> size;

  size = size + 1;
  int tab3[size];

  tab3[0] = 5;
  std         


        

Answer 1

Variable-length arrays in C++ are available as an extension in GCC. Compiling with all warnings should have alerted you to that fact (include -pedantic).

Answer 2

It is a C99 feature, not a part of C++. They are commonly refered to as VLAs(Variable Length Arrays.

If you run g++ with -pedantic it will be rejected.

See GCC docs for more info.

See also: VLAs are evil.

Answer 3

GCC provide's VLA's or variable length arrays. A better practice is to create a pointer and use the new keyword to allocate space. VLA's are not available in MSVC, so the second option is better for cross platform code