What is the difference between std::fill and std::fill_n?

Question

Accepted Answer

**fill** — fill range. **fill_n** — fill n elements from iterator. **std::fill:** - Fills range [first, last). ```cpp std::vector v(5); std::fill(v.begin(), v.end(), 42); // v: 42, 42, 42, 42, 42 ``` **std::fill_n:** - Fills n elements starting from iterator. ```cpp std::vector v(10); std::fill_n(v.begin(), 5, 42); // v: 42, 42, 42, 42, 42, 0, 0, 0, 0, 0 ``` **Similar algorithms:** - `std::generate` — fill with generator function. - `std::generate_n` — generate n elements. - `std::iota` — fill with sequential values.

C++: What is the difference between std::fill and std::fill_n?