replace_if (STL Sample)

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

Required Header:
<algorithm>

template<class ForwardIterator, class Predicate, class Type> inline
     void replace_if(ForwardIterator first, ForwardIterator last, Predicate pred, const Type& 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_if algorithm replaces all elements from the range [first, last) that cause the predicate to return true with value.

Sample Code:

//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// replace_if.cpp : Illustrates how to use the replace_if function.
//
// Functions:
//
//    replace_if - Replace all elements from the sequence that
//                 satisfies a predicate with a specified 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 VECTOR_SIZE = 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 ;

    IntVector Numbers(VECTOR_SIZE) ;   //vector containing numbers

    IntVectorIt start, end, it ;

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

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

    //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 ;

    cout << "Before calling replace_if" << endl ;

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

    // replace all elements from Numbers that are <= 10 with 4
     replace_if(start, end, bind2nd(less_equal<int>(), 10), 4 ) ;

    cout << "After calling replace_if" << endl ;

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

}

 

Program Output is:

Before calling replace_if
Numbers { 10 20 10 15 12 7 9 10  }

After calling replace_if
Numbers { 4 20 4 15 12 4 4 4  }