std::ranges::replace_copy, std::ranges::replace_copy_if, std::ranges::replace_copy_result, std::ranges::replace_copy_if_result

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Algorithm library

Constrained algorithms and algorithms on ranges (C++20)
Constrained algorithms, e.g. ranges::copy, ranges::sort, ...
Execution policies (C++17)
is_execution_policy (C++17)   execution::seqexecution::parexecution::par_unseqexecution::unseq (C++17)    (C++17)(C++17)(C++20)	execution::sequenced_policyexecution::parallel_policyexecution::parallel_unsequenced_policyexecution::parallel_unsequenced (C++17)(C++17)(C++17)(C++20)
Non-modifying sequence operations Batch operations for_each for_each_n (C++17) Search operations all_ofany_ofnone_of (C++11)                (C++11)(C++11) countcount_if mismatch equal findfind_iffind_if_not (C++11) find_end find_first_of adjacent_find search search_n Modifying sequence operations Copy operations copycopy_if (C++11) copy_backward copy_n (C++11) move (C++11) move_backward (C++11) Swap operations swap iter_swap swap_ranges Transformation operations replacereplace_if transform replace_copyreplace_copy_if Generation operations fill fill_n generate generate_n Removing operations removeremove_if unique remove_copyremove_copy_if unique_copy Order-changing operations reverse reverse_copy rotate rotate_copy random_shuffleshuffle (until C++17)(C++11) shift_leftshift_right (C++20)(C++20) Sampling operations sample (C++17)	Sorting and related operations Partitioning operations partition partition_copy (C++11)   stable_partition is_partitioned (C++11) partition_point (C++11) Sorting operations sort stable_sort partial_sort partial_sort_copy is_sorted (C++11) is_sorted_until (C++11) nth_element Binary search operations (on partitioned ranges) lower_bound upper_bound equal_range binary_search Set operations (on sorted ranges) includes set_union set_intersection set_difference set_symmetric_difference Merge operations (on sorted ranges) merge inplace_merge Heap operations push_heap pop_heap make_heap sort_heap is_heap (C++11) is_heap_until (C++11) Minimum/maximum operations max min minmax (C++11) clamp (C++17) max_element min_element minmax_element (C++11) Lexicographical comparison operations lexicographical_compare lexicographical_compare_three_way (C++20) Permutation operations next_permutation prev_permutation is_permutation (C++11) C library qsort bsearch
Numeric operations
iota (C++11) inner_product adjacent_difference    accumulate reduce (C++17) transform_reduce (C++17)	partial_sum inclusive_scan (C++17)    exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
Operations on uninitialized memory
uninitialized_copy uninitialized_move (C++17)    uninitialized_fill uninitialized_copy_n (C++11) uninitialized_move_n (C++17) uninitialized_fill_n	destroy (C++17) destroy_n (C++17) destroy_at (C++17) construct_at (C++20)       uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17)

 

Constrained algorithms

All names in this menu belong to namespace std::ranges

Non-modifying sequence operations

all_ofany_ofnone_of for_each for_each_n    countcount_if adjacent_find mismatch equal lexicographical_compare    containscontains_subrange (C++23)(C++23) findfind_iffind_if_not find_lastfind_last_iffind_last_if_not (C++23)(C++23)(C++23)   find_end find_first_of search search_n starts_with (C++23) ends_with (C++23)

Modifying sequence operations

copycopy_if copy_n copy_backward    move move_backward shift_leftshift_right (C++23)(C++23)   fill fill_n generate generate_n    transform swap_ranges    shuffle sample removeremove_if replacereplace_if reverse rotate remove_copyremove_copy_if    unique replace_copyreplace_copy_if reverse_copy rotate_copy unique_copy

Partitioning operations

is_partitioned    partition_point    partition    partition_copy    stable_partition

Sorting operations

is_sorted is_sorted_until     sort stable_sort         partial_sort       nth_element partial_sort_copy

Binary search operations (on sorted ranges)

lower_bound         upper_bound         binary_search      equal_range

Set operations (on sorted ranges)

merge inplace_merge       set_difference set_intersection    set_union          includes set_symmetric_difference

Heap operations

is_heap is_heap_until       make_heap           sort_heap push_heap pop_heap

Minimum/maximum operations

max max_element         min min_element         minmax minmax_element     clamp

Permutation operations

is_permutation      next_permutation    prev_permutation

Fold operations

fold_left (C++23) fold_left_first (C++23)   fold_right (C++23) fold_right_last (C++23)   fold_left_with_iter (C++23) fold_left_first_with_iter (C++23)

Numeric operations iota (C++23)             Random number generation generate_random (C++26)

Operations on uninitialized storage

construct_at    destroy destroy_n destroy_at uninitialized_copy    uninitialized_move uninitialized_fill uninitialized_copy_n    uninitialized_move_n uninitialized_fill_n uninitialized_default_construct uninitialized_default_construct_n uninitialized_value_construct uninitialized_value_construct_n

Return types

in_fun_result in_in_result in_found_result    in_out_result in_in_out_result    in_out_out_result    min_max_result out_value_result (C++23) in_value_result (C++23)

 

Defined in header <algorithm>
Call signature
template< std::input_iterator I, std::sentinel_for<I> S, class T1, class T2,           std::output_iterator<const T2&> O, class Proj = std::identity > requires std::indirectly_copyable<I, O> &&          std::indirect_binary_predicate<ranges::equal_to,              std::projected<I, Proj>, const T1*> constexpr replace_copy_result<I, O>     replace_copy( I first, S last, O result, const T1& old_value, const T2& new_value,                   Proj proj = {} );	(1)	(since C++20)
template< ranges::input_range R, class T1, class T2,           std::output_iterator<const T2&> O, class Proj = std::identity > requires std::indirectly_copyable<ranges::iterator_t<R>, O> &&          std::indirect_binary_predicate<ranges::equal_to,              std::projected<ranges::iterator_t<R>, Proj>, const T1*> constexpr replace_copy_result<ranges::borrowed_iterator_t<R>, O>     replace_copy( R&& r, O result, const T1& old_value, const T2& new_value,                   Proj proj = {} );	(2)	(since C++20)
template< std::input_iterator I, std::sentinel_for<I> S, class T,           std::output_iterator<const T&> O, class Proj = std::identity,           std::indirect_unary_predicate<std::projected<I, Proj>> Pred > requires std::indirectly_copyable<I, O> constexpr replace_copy_if_result<I, O>     replace_copy_if( I first, S last, O result, Pred pred, const T& new_value,                      Proj proj = {} );	(3)	(since C++20)
template< ranges::input_range R, class T, std::output_iterator<const T&> O,           class Proj = std::identity,           std::indirect_unary_predicate<std::projected<ranges::iterator_t<R>, Proj>> Pred > requires std::indirectly_copyable<ranges::iterator_t<R>, O> constexpr replace_copy_if_result<ranges::borrowed_iterator_t<R>, O>     replace_copy_if( R&& r, O result, Pred pred, const T& new_value,                      Proj proj = {} );	(4)	(since C++20)
Helper types
template< class I, class O > using replace_copy_result = ranges::in_out_result<I, O>;	(5)	(since C++20)
template< class I, class O > using replace_copy_if_result = ranges::in_out_result<I, O>;	(6)	(since C++20)

Copies the elements from the source range [first, last) to the destination range beginning at result, replacing all elements satisfying specific criteria with new_value. The behavior is undefined if the source and destination ranges overlap.

1) Replaces all elements that are equal to old_value, using std::invoke(proj, *(first + (i - result))) == old_value to compare.

3) Replaces all elements for which the predicate pred evaluates to true, where the evaluating expression is std::invoke(pred, std::invoke(proj, *(first + (i - result)))).

2,4) Same as (1,3), 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 calling 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 inhibited.

In practice, they may be implemented as function objects, or with special compiler extensions.

Parameters

first, last	-	the range of elements to copy
r	-	the range of elements to copy
result	-	the beginning of the destination range
old_value	-	the value of elements to replace
new_value	-	the value to use as a replacement
pred	-	predicate to apply to the projected elements
proj	-	projection to apply to the elements.

Return value

{last, result + N}, where

1,3) N = ranges::distance(first, last);

2,4) N = ranges::distance(r).

Complexity

Exactly N applications of the corresponding predicate comp and any projection proj.

Possible implementation

First version
struct replace_copy_fn { template<std::input_iterator I, std::sentinel_for<I> S, class T1, class T2, std::output_iterator<const T2&> O, class Proj = std::identity> requires std::indirectly_copyable<I, O> && std::indirect_binary_predicate<ranges::equal_to, std::projected<I, Proj>, const T1*> constexpr ranges::replace_copy_result<I, O> operator()(I first, S last, O result, const T1& old_value, const T2& new_value, Proj proj = {}) const { for (; first != last; ++first, ++result) *result = (std::invoke(proj, *first) == old_value) ? new_value : *first; return {std::move(first), std::move(result)}; }   template<ranges::input_range R, class T1, class T2, std::output_iterator<const T2&> O, class Proj = std::identity> requires std::indirectly_copyable<ranges::iterator_t<R>, O> && std::indirect_binary_predicate<ranges::equal_to, std::projected<ranges::iterator_t<R>, Proj>, const T1*> constexpr ranges::replace_copy_result<ranges::borrowed_iterator_t<R>, O> operator()(R&& r, O result, const T1& old_value, const T2& new_value, Proj proj = {}) const { return (*this)(ranges::begin(r), ranges::end(r), std::move(result), old_value, new_value, std::move(proj)); } };   inline constexpr replace_copy_fn replace_copy {};
Second version
struct replace_copy_if_fn { template<std::input_iterator I, std::sentinel_for<I> S, class T, std::output_iterator<const T&> O, class Proj = std::identity, std::indirect_unary_predicate< std::projected<I, Proj>> Pred> requires std::indirectly_copyable<I, O> constexpr ranges::replace_copy_if_result<I, O> operator()(I first, S last, O result, Pred pred, const T& new_value, Proj proj = {}) const { for (; first != last; ++first, ++result) *result = std::invoke(pred, std::invoke(proj, *first)) ? new_value : *first; return {std::move(first), std::move(result)}; }   template<ranges::input_range R, class T, std::output_iterator<const T&> O, class Proj = std::identity, std::indirect_unary_predicate<std::projected<ranges::iterator_t<R>, Proj>> Pred> requires std::indirectly_copyable<ranges::iterator_t<R>, O> constexpr ranges::replace_copy_if_result<ranges::borrowed_iterator_t<R>, O> operator()(R&& r, O result, Pred pred, const T& new_value, Proj proj = {}) const { return (*this)(ranges::begin(r), ranges::end(r), std::move(result), std::move(pred), new_value, std::move(proj)); } };   inline constexpr replace_copy_if_fn replace_copy_if {};

Example

Run this code

#include <algorithm>
#include <array>
#include <iostream>
#include <vector>
 
int main()
{
    auto print = [](const auto rem, const auto& v)
    {
        for (std::cout << rem << ": "; const auto& e : v)
            std::cout << e << ' ';
        std::cout << '\n';
    };
 
    std::vector<int> o;
 
    std::array p {1, 6, 1, 6, 1, 6};
    o.resize(p.size());
    print("p", p);
    std::ranges::replace_copy(p, o.begin(), 6, 9);
    print("o", o);
 
    std::array q {1, 2, 3, 6, 7, 8, 4, 5};
    o.resize(q.size());
    print("q", q);
    std::ranges::replace_copy_if(q, o.begin(), [](int x) { return 5 < x; }, 5);
    print("o", o);
}

Output:

p: 1 6 1 6 1 6 
o: 1 9 1 9 1 9 
q: 1 2 3 6 7 8 4 5 
o: 1 2 3 5 5 5 4 5

See also

ranges::replaceranges::replace_if (C++20)(C++20)	replaces all values satisfying specific criteria with another value (niebloid)
replace_copyreplace_copy_if	copies a range, replacing elements satisfying specific criteria with another value (function template)