std::remove_copy, std::remove_copy_if - cppreference.com (original) (raw)

Copies elements from the range [first, last), to another range beginning at d_first, omitting the elements which satisfy specific criteria.

1. Ignores all elements that are equal to value (using operator==).

2. Ignores all elements for which predicate p returns true.

2,4) Same as (1,3), but executed according to policy.

These overloads participate in overload resolution only if all following conditions are satisfied:

If *d_first = *first is invalid(until C++20)*first is not writable to d_first(since C++20), the program is ill-formed.

If source and destination ranges overlap, the behavior is undefined.

Contents

• 1 Parameters
• 2 Return value
• 3 Complexity
• 4 Exceptions
• 5 Possible implementation
• 6 Notes
• 7 Example
• 8 Defect reports
• 9 See also

[edit] Parameters

[edit] Return value

Iterator to the element past the last element copied.

[edit] Complexity

Given \(\scriptsize N\)N as std::distance(first, last):

1,2) Exactly \(\scriptsize N\)N comparisons with value using operator==.

3,4) Exactly \(\scriptsize N\)N applications of the predicate p.

For the overloads with an ExecutionPolicy, there may be a performance cost if ForwardIt1's value_type is not MoveConstructible.

[edit] Exceptions

The overloads with a template parameter named ExecutionPolicy report errors as follows:

• If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the standard policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
• If the algorithm fails to allocate memory, std::bad_alloc is thrown.

[edit] Possible implementation

[edit] Notes

[edit] Example

#include #include #include #include #include #include #include   int main() { // Erase the hash characters '#' on the fly. std::string str = "#Return #Value #Optimization"; std::cout << "before: " << std::quoted(str) << '\n';   std::cout << "after: ""; std::remove_copy(str.begin(), str.end(), std::ostream_iterator(std::cout), '#'); std::cout << ""\n";   // Erase {1, 3} value on the fly. std::vector<std::complex> nums{{2, 2}, {1, 3}, {4, 8}, {1, 3}}; std::remove_copy(nums.begin(), nums.end(), std::ostream_iterator<std::complex>(std::cout), #ifdef __cpp_lib_algorithm_default_value_type {1, 3}); // T gets deduced #else std::complex{1, 3}); #endif }

Output:

before: "#Return #Value #Optimization" after: "Return Value Optimization" (2,2)(4,8)

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also