std::replace, std::replace_if

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Defined in header <algorithm>

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template< class ForwardIterator, class T >

void replace( ForwardIterator first, ForwardIterator last,

              const T& old_value, const T& new_value );

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template< class ForwardIterator, class UnaryPredicate, class T >

void replace_if( ForwardIterator first, ForwardIterator last,

                 UnaryPredicate p, const T& new_value );

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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 Template:cpp.

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 expression p(v) must be convertible to bool for every argument v of type (possibly const) VT, where VT is the value type of ForwardIterator, regardless of value category, and must not modify v. Thus, a parameter type of VT&is not allowed, nor is VT unless for VT a move is equivalent to a copy(since C++11). ​
new_value	-	the value to use as replacement

Return value

(none)

Complexity

Exactly last - first applications of the predicate.

Example

The following code at first replaces all occurrences of Template:cpp with Template:cpp in a vector of integers. Then it replaces all values less than Template:cpp with 55.

Run this code

#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 99 6 55 9 55 55

See also

Template:cpp/algorithm/dcl list replace copy