function template
<algorithm>
std::replace_copy_if
template <class InputIterator, class OutputIterator, class UnaryPredicate, class T> OutputIterator replace_copy_if (InputIterator first, InputIterator last, OutputIterator result, UnaryPredicate pred, const T& new_value);
Copy range replacing value
Copies the elements in the range [first,last) to the range beginning at result, replacing those for which pred returns true by new_value.
此函数模板的行为等同于
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template <class InputIterator, class OutputIterator, class UnaryPredicate, class T>
OutputIterator replace_copy_if (InputIterator first, InputIterator last,
OutputIterator result, UnaryPredicate pred,
const T& new_value)
{
while (first!=last) {
*result = (pred(*first))? new_value: *first;
++first; ++result;
}
return result;
}
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参数
- first, last
- Input iterators to the initial and final positions in a sequence. The range copied is
[first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
- result
- Output iterator to the initial position of the range where the resulting sequence is stored. The range includes as many elements as
[first,last).
The pointed type shall support being assigned a value of type T.
- pred
- Unary function that accepts an element in the range as argument, and returns a value convertible to
bool. The value returned indicates whether the element is to be replaced in the copy (if true, it is replaced).
该函数不得修改其参数。
This can either be a function pointer or a function object.
- new_value
- Value to assign to replaced values.
这些范围不应重叠。
返回值
一个指向结果序列中最后一个写入元素的下一个元素的迭代器。
示例
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// replace_copy_if example
#include <iostream> // std::cout
#include <algorithm> // std::replace_copy_if
#include <vector> // std::vector
bool IsOdd (int i) { return ((i%2)==1); }
int main () {
std::vector<int> foo,bar;
// set some values:
for (int i=1; i<10; i++) foo.push_back(i); // 1 2 3 4 5 6 7 8 9
bar.resize(foo.size()); // allocate space
std::replace_copy_if (foo.begin(), foo.end(), bar.begin(), IsOdd, 0);
// 0 2 0 4 0 6 0 8 0
std::cout << "bar contains:";
for (std::vector<int>::iterator it=bar.begin(); it!=bar.end(); ++it)
std::cout << ' ' << *it;
std::cout << '\n';
return 0;
}
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输出
second contains: 0 2 0 4 0 6 0 8 0
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复杂度
Linear in the distance between first and last: Applies pred and performs an assignment for each element.
数据竞争
访问范围 [first,last) 中的对象。
修改 result 和返回的迭代器之间的范围内的对象。
异常
如果 pred、元素赋值或迭代器操作抛出异常，则此函数也抛出异常。
请注意，无效参数会导致未定义行为。