replace_copy_if (STL Sample)

The sample code below illustrates how to use the replace_copy_if STL function in Visual C++.

Required Header:
<algorithm>

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

Note: The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.

Description:
The replace_copy_if algorithm copies all elements from the range [first, last) to a same-size range starting at result, replacing all occurrences that cause the predicate to return true with new_value in the resulting sequence. It returns an iterator positioned immediately after the last new element in the resulting sequence.

Sample Code:

//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// replace_copy_if.cpp : Illustrates how to use the replace_copy_if
//                       function.
//
// Functions:
//
//    replace_copy_if - Copy the elements of a sequence to another
//                      same-size sequence replacing any elements
//                      that satisfies a predicate, with another value.
//
//////////////////////////////////////////////////////////////////////

// disable warning C4786: symbol greater than 255 characters,
// okay to ignore
#pragma warning(disable: 4786)

#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>

using namespace std;


void main()
{
    const int MAX_ELEMENTS = 8 ;

    // Define a template class vector of integers
    typedef vector<int > IntVector ;

    //Define an iterator for template class vector of integer
    typedef IntVector::iterator IntVectorIt ;

    //vector containing numbers
    IntVector Numbers(MAX_ELEMENTS), Result(MAX_ELEMENTS) ;

    IntVectorIt start, end, it, last, resultIt ;

    //Initialize vector Numbers
    Numbers[0] = 10 ;
    Numbers[1] = 20 ;
    Numbers[2] = 10 ;
    Numbers[3] = 15 ;
    Numbers[4] = 12 ;
    Numbers[5] = 7 ;
    Numbers[6] = 9 ;
    Numbers[7] = 10 ;

    start = Numbers.begin() ;   // location of first
                                // element of Numbers

    end = Numbers.end() ;       // one past the location
                                // last element of Numbers

    resultIt = Result.begin() ; // location of first
                                // element of Result

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

    // copy all elements from Numbers to Result
    // replacing any item that >= 10 with 30
    last = replace_copy_if(start, end, resultIt,
                           bind2nd(greater_equal<int>(), 10), 30) ;

    //print number of elements copied to Result
    cout << "Total number of elements copied to Result = "
        << last - resultIt << endl ;

    start = Result.begin() ;   // location of first
                                // element of Result

    end = Result.end() ;       // one past the location
                               // last element of Result

    // print content of Result
    cout << "Result  { " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

}

 

Program Output is:

Numbers { 10 20 10 15 12 7 9 10  }

Total number of elements copied to Result = 8
Result  { 30 30 30 30 30 7 9 30  }