## replace_copy_if

    Algorithm

- Summary
- Data Type and Member Function Indexes
- Synopsis
- Description
- Complexity
- Example
- Warnings
- See Also

### Summary

Substitutes elements in a collection with new values, and moves the revised sequence into `result`.

### Data Type and Member Function Indexes
(exclusive of constructors and destructors)

None

### Synopsis

    #include <algorithm>
    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

The replace_copy_if algorithm leaves the original sequence intact and places a revised sequence into `result`. For the range `[first,last)`, the algorithm compares each element `*i` with the conditions specified by `pred`. If `pred(*i)==false`, replace_copy_if copies `*i` to `result+(first-i)`. If `pred(*i)==true`, then replace_copy copies `new_value` to `result+(first-i)`. replace_copy_if returns `result+(last-first)`.

### Complexity

Exactly `last - first` applications of the predicate are performed.

### Example

    //
    // replace.cpp
    //
     #include <algorithm>
     #include <vector>
     #include <iterator>
     #include <iostream>
     using namespace std;

     template<class Arg>
     struct all_true : public unary_function<Arg, bool>
     {
       bool operator() (const Arg&) { return 1; }
     };

     int main ()
     {
       //
       // Initialize a vector with an array of integers.
       //
       int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
       vector<int> v(arr+0, arr+10);
       //
       // Print out original vector.
       //
       cout << "The original list: " << endl << "     ";
       copy(v.begin(), v.end(),
            ostream_iterator<int,char>(cout," "));
       cout << endl << endl;
       //
       // Replace the number 7 with 11.
       //
       replace(v.begin(), v.end(), 7, 11);
       //
       // Print out vector with 7 replaced.
       //
       cout << "List after replace:" << endl << "     ";
       copy(v.begin(), v.end(),
            ostream_iterator<int,char>(cout," "));
       cout << endl << endl;
       //
       // Replace 1 2 3 with 13 13 13.
       //
       replace_if(v.begin(), v.begin()+3, all_true<int>(), 13);
       //
       // Print out the remaining vector.
       //
       cout << "List after replace_if:" << endl << "     ";
       copy(v.begin(), v.end(),
            ostream_iterator<int,char>(cout," "));
       cout << endl << endl;
       //
       // Replace those 13s with 17s on output.
       //
       cout << "List using replace_copy to cout:" << endl
            << "     ";
       replace_copy(v.begin(), v.end(),
                    ostream_iterator<int,char>(cout, " "),
                    13, 17);
       cout << endl << endl;
       //
       // A simple example of replace_copy_if.
       //
       cout << "List w/ all elements output as 19s:" << endl
           << "   ";
       replace_copy_if(v.begin(), v.end(),
                       ostream_iterator<int,char>(cout, " "),
                       all_true<int>(), 19);
       cout << endl;

       return 0;
     }

Program Output

    The original list:
         1 2 3 4 5 6 7 8 9 10
    List after replace:
         1 2 3 4 5 6 11 8 9 10
    List after replace_if:
         13 13 13 4 5 6 11 8 9 10
    List using replace_copy to cout:
         17 17 17 4 5 6 11 8 9 10
    List with all elements output as 19s:
         19 19 19 19 19 19 19 19 19 19

### Warnings

If your compiler does not support default template parameters, then you always need to supply the `Allocator` template argument. For instance, you need to write:

`vector<int, allocator<int> >`

instead of:

`vector<int>`

If your compiler does not support namespaces, then you do not need the using declaration for `std`.

### See Also

replace, replace_if, replace_copy

Copyright (c) 1998, Rogue Wave Software, Inc.
Send mail to report errors or comment on the documentation.
OEM Release, June 1998