Re: Extending std::iota function

Ricky65 <>
Sat, 9 Jul 2011 02:41:26 CST
On Jul 7, 6:14 pm, CornedBee <> wrote:

On Jul 5, 3:33 am, Ricky65 <> wrote:

In C++0x the iota function has been added which I find very useful for
testing. However, I find the ability to only increment by 1 to be very
limiting. Sometimes we don't want to fill a container or array with
consecutive integers, we want to control the increment. Consequently,
I feel it would be useful to provide an overload for iota with this

You could always overload increment.

template <typename Base, typename Step>
class stepper {
  const Step stepsize;
  Base value;
  stepper(Step stepsize, Base initial) : stepsize(stepsize),
value(initial) {}
  stepper& operator ++() { value += stepsize; return *this; }
  stepper operator ++(int) { stepper tmp(*this); ++*this; return
tmp; }};

template <typename Base, typename Step>
stepper<Base, Step> step(Base initial, Step stepsize) {
  return stepper<Base, Step>(stepsize, initial);


std::vector<int> v(10);
std::iota(v.begin(), v.end(), step(0, 5));
// gives 0, 5, 10, 15, ...

But in such cases, a std::generate or std::generate_n with a stateful
generator may be a better solution.

{ trailing quoted signature and banner removed -mod }

Yes you could overload operator ++ as you have shown but that is a lot
more verbose, as is std::generate and std::generate_n with a stateful
The iota overload I provided is a lot more concise and cleaner I feel.


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