std::replace, std::replace_if
From Cppreference
| Defined in header
<algorithm> | ||
| template< class ForwardIterator, class T >
void replace( ForwardIterator first, ForwardIterator last, | (1) | |
| template< class ForwardIterator, class UnaryPredicate, class T >
void replace_if( ForwardIterator first, ForwardIterator last, | (2) | |
Replaces all elements satisfying specific criteria with new_value in the range [first, last). The first version replaces the elements that are equal to old_value, the second version replaces elements for which predicate p returns true.
Contents |
[edit] Parameters
| first, last | - | the range of elements to process | |||||||||
| old_value | - | the value of elements to replace | |||||||||
| p | - | unary predicate which returns true if the element value should be replaced. The signature of the predicate function should be equivalent to the following:
The signature does not need to have const &, but the function must not modify the objects passed to it. | |||||||||
| new_value | - | the value to use as replacement | |||||||||
[edit] Return value
(none)
[edit] Complexity
linear in the distance between first and last
[edit] Equivalent function
| First version: |
|---|
template<class ForwardIterator, class T> void replace(ForwardIterator first, ForwardIterator last, const T& old_value, const T& new_value) { for (; first != last; ++first) { if (*first == old_value) { *first = new_value; } } } |
| Second version: |
template<class ForwardIterator, class UnaryPredicate, class T> void replace_if(ForwardIterator first, ForwardIterator last, UnaryPredicate p, const T& new_value) { for (; first != last; ++first) { if(p(*first)) { *first = new_value; } } } |
[edit] Example
#include <algorithm> #include <array> #include <iostream> #include <functional> int main() { std::array<int> s{5, 7, 4, 2, 8, 6, 1, 9, 0, 3}; std::replace(s.begin(), s.end(), 8, 99); for (int a : s) { std::cout << a << " "; } std::cout << endl; std::replace_if(s.begin(), s.end(), std::bind(std::less<int>(), 5), 99); for (int a : s) { std::cout << a << " "; } return 0; }
Output:
5 7 4 2 99 6 1 9 0 3 5 7 99 99 99 6 99 9 99 99
[edit] See also
| copies a range, replacing elements satisfying specific criteria with another value (function template) | |
