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replace_copy_if


Category: algorithms	Component type: function

Prototype

template <class InputIterator, class OutputIterator, class Predicate, class T>
OutputIterator replace_copy_if(InputIterator first, InputIterator last,
                               OutputIterator result, Predicate pred,
                               const T& new_value)

Description

Replace_copy_if copies elements from the range [first, last) to the range [result, result + (last-first)), except that any element for which pred is true is not copied; new_value is copied instead. More precisely, for every integer n such that 0 <= n < last-first, replace_copy_if performs the assignment *(result+n) = new_value if pred(*(first+n)), and *(result+n) = *(first+n) otherwise.

Definition

Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h.

Requirements on types

InputIterator is a model of Input Iterator.
OutputIterator is a model of Output Iterator.
Predicate is a model of Predicate.
T is convertible to Predicate's argument type.
T is Assignable.
T is convertible to a type in OutputIterator's set of value types.

Preconditions

[first, last) is a valid range.
There is enough space in the output range to store the copied values. That is, [result, result + (last-first)) is a valid range.
result is not an iterator within the range [first, last).

Complexity

Linear. Replace_copy performs exactly last - first applications of pred and exactly last - first assignments.

Example

Copy elements from one vector to another, replacing all negative numbers with 0.

vector<int> V1;
V1.push_back(1);
V1.push_back(-1);
V1.push_back(-5);
V1.push_back(2);

vector<int> V2(4);

replace_copy_if(V1.begin(), V1.end(), V2.begin(),
                bind2nd(less<int>(), 0),
                0);
assert(V[0] == 1 && V[1] == 0 && V[2] == 0 && V[3] == 2);