Question

Can I initialize a vector<bool> to start with a sequence of 010101…etc? Or do I have to just initialize it with 0’s and loop thru and change every other value to 1?

Answer 1

To expand on @zmbq’s answer, use std::generate_n like this:

std::vector<bool> v;
v.reserve(desired_size);

bool b = true;
std::generate_n(std::back_inserter(v), desired_size, [&b]() { return (b = !b); });

You would use std::generate if the vector already had a size.

If you don’t have a C++11 compiler…

std::vector<bool> v;
v.reserve(desired_size);

struct GenFn
{
   GenFn(bool b = true)
      : b(b)
   {
   }

   bool operator()() const
   {
      return (b = !b);
   }

private:
   bool b;
};

std::generate_n(std::back_inserter(v), desired_size, GenFn());