C++ specify array indexes in initializer, like C

Question

I used C before (embedded stuff), and I can initialize my arrays like that:

int widths[] = { [0 ... 9] = 1, [10 ... 99] = 2, [100] = 3 };

i

Answer 1

No, it is not possible to do it in C++ like that. But you can use std::fill algorithm to assign the values:

int widths[101];
fill(widths, widths+10, 1);
fill(widths+10, widths+100, 2);
fill(widths+100, widths+101, 3);

It is not as elegant, but it works.

Answer 2

After years, I tested it just by chance, and I can confirm that it works in g++ -std=c++11, g++ version is 4.8.2.

Answer 3

hm, you should use std::fill_n() for that task...

as stated here http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html the designated inits (extention) are not implemented in GNU C++

edit: taken from here: initialize a const array in a class initializer in C++

as a comment said, you can use std:vector to get the result desired. You could still enforce the const another way around and use fill_n.

int* a = new int[N];
// fill a

class C {
  const std::vector<int> v;
public:
  C():v(a, a+N) {}
};