| Defined in header <algorithm> | ||
|---|---|---|
template< class ForwardIt, class T >
void replace( ForwardIt first, ForwardIt last,
const T& old_value, const T& new_value ); | (1) | |
template< class ForwardIt, class UnaryPredicate, class T >
void replace_if( ForwardIt first, ForwardIt last,
UnaryPredicate p, const T& new_value ); | (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.
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 |
| new_value | - | the value to use as replacement |
| Type requirements | ||
- ForwardIt must meet the requirements of ForwardIterator. | ||
- UnaryPredicate must meet the requirements of Predicate. | ||
Return value
(none).
Complexity
Exactly last - first applications of the predicate.
Possible implementation
| First version |
|---|
template<class ForwardIt, class T>
void replace(ForwardIt first, ForwardIt last,
const T& old_value, const T& new_value)
{
for (; first != last; ++first) {
if (*first == old_value) {
*first = new_value;
}
}
} |
| Second version |
template<class ForwardIt, class UnaryPredicate, class T>
void replace_if(ForwardIt first, ForwardIt last,
UnaryPredicate p, const T& new_value)
{
for (; first != last; ++first) {
if(p(*first)) {
*first = new_value;
}
}
} |
Example
The following code at first replaces all occurrences of 8 with 88 in a vector of integers. Then it replaces all values less than 5 with 55.
#include <algorithm>
#include <array>
#include <iostream>
#include <functional>
int main()
{
std::array<int, 10> s{5, 7, 4, 2, 8, 6, 1, 9, 0, 3};
std::replace(s.begin(), s.end(), 8, 88);
for (int a : s) {
std::cout << a << " ";
}
std::cout << '\n';
std::replace_if(s.begin(), s.end(),
std::bind(std::less<int>(), std::placeholders::_1, 5), 55);
for (int a : s) {
std::cout << a << " ";
}
std::cout << '\n';
}Output:
5 7 4 2 88 6 1 9 0 3 5 7 55 55 88 6 55 9 55 55
See also
| copies a range, replacing elements satisfying specific criteria with another value (function template) | |
| std::experimental::parallel::replace
(parallelism TS) | parallelized version of std::replace (function template) |
| std::experimental::parallel::replace_if
(parallelism TS) | parallelized version of std::replace_if (function template) |
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