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std::ranges::fill(3) C++ Standard Libary std::ranges::fill(3) NAME std::ranges::fill - std::ranges::fill Synopsis Defined in header <algorithm> Call signature template< class T, std::output_iterator<const T&> O, std::sentinel_for<O> S > (since C++20) constexpr O fill( O first, S last, const T& (until C++26) value ); template< class O, std::sentinel_for<O> S, class T = std::iter_value_t<O> > requires std::output_iterator<O, const T&> (since C++26) constexpr O fill( O first, S last, const T& value ); (1) template< class T, ranges::output_range<const T&> R > (since C++20) constexpr ranges::borrowed_iterator_t<R> fill( (until C++26) R&& r, const T& value ); template< class R, class T = std::range_value_t<R> > (2) requires ranges::output_range<R, const T&> (since C++26) constexpr ranges::borrowed_iterator_t<R> fill( R&& r, const T& value ); 1) Assigns the given value to the elements in the range [first, last). 2) Same as (1), but uses r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last. The function-like entities described on this page are niebloids, that is: * Explicit template argument lists cannot be specified when call- ing any of them. * None of them are visible to argument-dependent lookup. * When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is in- hibited. In practice, they may be implemented as function objects, or with special compiler extensions. Parameters first, last - the range of elements to modify r - the range of elements to modify value - the value to be assigned Return value An output iterator that compares equal to last. Complexity Exactly last - first assignments. Possible implementation struct fill_fn { template<class O, std::sentinel_for<O> S, class T = std::iter_value_t<O>> requires std::output_iterator<O, const T&> constexpr O operator()(O first, S last, const T& value) const { while (first != last) *first++ = value; return first; } template<class R, class T = std::range_value_t<R>> requires ranges::output_range<R, const T&> constexpr ranges::borrowed_iterator_t<R> operator()(R&& r, const T& value) const { return (*this)(ranges::begin(r), ranges::end(r), value); } }; inline constexpr fill_fn fill; Notes Feature-test macro Value Std Feature __cpp_lib_algorithm_default_value_type 202403 (C++26) List-initial- ization for algorithms (1,2) Example // Run this code #include <algorithm> #include <complex> #include <iostream> #include <vector> void println(const auto& seq) { for (const auto& e : seq) std::cout << e << ' '; std::cout << '\n'; } int main() { std::vector<int> v{0, 1, 2, 3, 4, 5}; // set all elements to -1 using overload (1) std::ranges::fill(v.begin(), v.end(), -1); println(v); // set all element to 10 using overload (2) std::ranges::fill(v, 10); println(v); std::vector<std::complex<double>> nums{{1, 3}, {2, 2}, {4, 8}}; println(nums); #ifdef __cpp_lib_algorithm_default_value_type std::ranges::fill(nums, {4, 2}); // T gets deduced #else std::ranges::fill(nums, std::complex<double>{4, 2}); #endif println(nums); } Output: -1 -1 -1 -1 -1 -1 10 10 10 10 10 10 (1,3) (2,2) (4,8) (4,2) (4,2) (4,2) See also ranges::fill_n assigns a value to a number of elements (C++20) (niebloid) ranges::copy ranges::copy_if copies a range of elements to a new location (C++20) (niebloid) (C++20) ranges::generate saves the result of a function in a range (C++20) (niebloid) ranges::transform applies a function to a range of elements (C++20) (niebloid) ranges::generate_random fills a range with random numbers from a uniform random bit (C++26) generator (niebloid) fill copy-assigns the given value to every ele- ment in a range (function template) http://cppreference.com 2024.06.10 std::ranges::fill(3)
NAME | Synopsis | Parameters | Return value | Complexity | Possible implementation | Notes | Example | Output: | See also
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