Difference between revisions of "cpp/algorithm/replace copy"
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template<class InputIterator, class OutputIterator, class T> | template<class InputIterator, class OutputIterator, class T> | ||
Revision as of 04:22, 3 July 2012
Template:ddcl list begin <tr class="t-dsc-header">
<td><algorithm>
<td></td> <td></td> </tr> <tr class="t-dcl ">
<td >OutputIterator replace_copy( InputIterator first,
InputIterator last,
OutputIterator d_first,
const T& old_value,
<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">
<td >OutputIterator replace_copy_if( InputIterator first,
InputIterator last,
OutputIterator d_first,
UnaryPredicate p,
<td > (2) </td> <td class="t-dcl-nopad"> </td> </tr> Template:ddcl list end
Copies the all elements from the range [first, last) to another range beginning at d_first replacing all elements satisfying specific criteria with new_value. The first version replaces the elements that are equal to old_value, the second version replaces elements for which predicate p returns true. The source and destination ranges cannot overlap.
Contents |
Parameters
| first, last | - | the range of elements to copy |
| d_first | - | the beginning of the destination range |
| old_value | - | the value of elements to replace |
| p | - | unary predicate which returns true if the element value should be replaced. The expression p(v) must be convertible to bool for every argument |
| new_value | - | the value to use as replacement |
Return value
iterator to the element past the last element copied.
Complexity
Exactly last - first applications of the predicate.
Possible implementation
| First version |
|---|
template<class InputIterator, class OutputIterator, class T> OutputIterator replace_copy(InputIterator first, InputIterator last, OutputIterator d_first, const T& old_value, const T& new_value) { for (; first != last; ++first) { *d_first++ = (*first == old_value) ? new_value : *first; } return d_first; } |
| Second version |
template<class InputIterator, class OutputIterator, class UnaryPredicate, class T> OutputIterator replace_copy_if(InputIterator first, InputIterator last, OutputIterator d_first, UnaryPredicate p, const T& new_value) { for (; first != last; ++first) { *d_first++ = (p( *first ) ? new_value : *first; } return d_first; } |
Example
The following copy prints a vector, replacing all values over 5 with 99 on the fly.
#include <algorithm> #include <vector> #include <iostream> #include <iterator> #include <functional> int main() { std::vector<int> v{5, 7, 4, 2, 8, 6, 1, 9, 0, 3}; std::replace_copy_if(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "), [](int n){return n > 5;}, 99); std::cout << '\n'; }
Output:
5 99 4 2 99 99 1 99 0 3
