std::ranges::replace_copy, std::ranges::replace_copy_if, std::ranges::replace_copy_result, std::ranges::replace_copy_if_result
From cppreference.com
| Defined in header <algorithm>
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| Call signature |
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| (1) | ||
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 = {} );
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(since C++20) (until C++26) |
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template< std::input_iterator I, std::sentinel_for<I> S,
class O, class Proj = std::identity,
class T1 = std::projected_value_t<I, Proj>,
class T2 = std::iter_value_t<O> >
requires std::indirectly_copyable<I, O> &&
std::indirect_binary_predicate
<ranges::equal_to, std::projected<I, Proj>, const T1*> &&
std::output_iterator<O, const T2&>
constexpr replace_copy_result<I, O>
replace_copy( I first, S last, O result, const T1& old_value,
const T2& new_value, Proj proj = {} );
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(since C++26) | |
| (2) | ||
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 = {} );
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(since C++20) (until C++26) |
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template< ranges::input_range R,
class O, class Proj = std::identity,
class T1 = std::projected_value_t<ranges::iterator_t<R>, Proj>,
class T2 = std::iter_value_t<O> >
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*> &&
std::output_iterator<O, const T2&>
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 = {} );
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(since C++26) | |
| (3) | ||
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 = {} );
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(since C++20) (until C++26) |
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template< std::input_iterator I, std::sentinel_for<I> S,
class O, class T = std::iter_value_t<O>
class Proj = std::identity,
std::indirect_unary_predicate<std::projected<I, Proj>> Pred >
requires std::indirectly_copyable<I, O> && std::output_iterator<O, const T&>
constexpr replace_copy_if_result<I, O>
replace_copy_if( I first, S last, O result, Pred pred,
const T& new_value, Proj proj = {} );
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(since C++26) | |
| (4) | ||
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 = {} );
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(since C++20) (until C++26) |
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template< ranges::input_range R,
class O, class T = std::iter_value_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> &&
std::output_iterator<O, const T&>
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 = {} );
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(since C++26) | |
| Helper types |
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template< class I, class O >
using replace_copy_result = ranges::in_out_result<I, O>;
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(5) | (since C++20) |
template< class I, class O >
using replace_copy_if_result = ranges::in_out_result<I, O>;
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(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 algorithm function objects (informally known as 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.
Parameters
| first, last | - | the iterator-sentinel pair defining 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
| replace_copy (1,2) |
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struct replace_copy_fn
{
template<std::input_iterator I, std::sentinel_for<I> S,
class O, class Proj = std::identity,
class T1 = std::projected_value_t<I, Proj>,
class T2 = std::iter_value_t<O>>
requires std::indirectly_copyable<I, O> &&
std::indirect_binary_predicate
<ranges::equal_to, std::projected<I, Proj>, const T1*> &&
std::output_iterator<O, const T2&>
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 O, class Proj = std::identity,
class T1 = std::projected_value_t<ranges::iterator_t<R>, Proj>,
class T2 = std::iter_value_t<O>>
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 {};
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| replace_copy_if (3,4) |
struct replace_copy_if_fn
{
template<std::input_iterator I, std::sentinel_for<I> S,
class O, class T = std::iter_value_t<O>
class Proj = std::identity,
std::indirect_unary_predicate<std::projected<I, Proj>> Pred>
requires std::indirectly_copyable<I, O> && std::output_iterator<O, const T&>
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 O, class T = std::iter_value_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> &&
std::output_iterator<O, const T&>
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 {};
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Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_algorithm_default_value_type |
202403 |
(C++26) | list-initialization for algorithms (1-4) |
Example
Run this code
#include <algorithm>
#include <array>
#include <complex>
#include <iostream>
#include <vector>
void println(const auto rem, const auto& v)
{
for (std::cout << rem << ": "; const auto& e : v)
std::cout << e << ' ';
std::cout << '\n';
}
int main()
{
std::vector<int> o;
std::array p{1, 6, 1, 6, 1, 6};
o.resize(p.size());
println("p", p);
std::ranges::replace_copy(p, o.begin(), 6, 9);
println("o", o);
std::array q{1, 2, 3, 6, 7, 8, 4, 5};
o.resize(q.size());
println("q", q);
std::ranges::replace_copy_if(q, o.begin(), [](int x) { return 5 < x; }, 5);
println("o", o);
std::vector<std::complex<short>> r{{1, 3}, {2, 2}, {4, 8}};
std::vector<std::complex<float>> s(r.size());
println("r", r);
#ifdef __cpp_lib_algorithm_default_value_type
std::ranges::replace_copy(r, s.begin(),
{1, 3}, // T1 gets deduced
{2.2, 4.8}); // T2 gets deduced
#else
std::ranges::replace_copy(r, s.begin(),
std::complex<short>{1, 3},
std::complex<float>{2.2, 4.8});
#endif
println("s", s);
std::vector<std::complex<double>> b{{1, 3}, {2, 2}, {4, 8}},
d(b.size());
println("b", b);
#ifdef __cpp_lib_algorithm_default_value_type
std::ranges::replace_copy_if(b, d.begin(),
[](std::complex<double> z){ return std::abs(z) < 5; },
{4, 2}); // Possible, since the T is deduced.
#else
std::ranges::replace_copy_if(b, d.begin(),
[](std::complex<double> z){ return std::abs(z) < 5; },
std::complex<double>{4, 2});
#endif
println("d", d);
}
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
r: (1,3) (2,2) (4,8)
s: (2.2,4.8) (2,2) (4,8)
b: (1,3) (2,2) (4,8)
d: (4,2) (4,2) (4,8)
See also
(C++20)(C++20) |
replaces all values satisfying specific criteria with another value (algorithm function object) |
| copies a range, replacing elements satisfying specific criteria with another value (function template) |