INFO: STL Sample for the for_each Function

ID: Q156345

The information in this article applies to:

The Standard C++ Library, used with:
- Microsoft Visual C++, 32-bit Editions, versions 4.2, 5.0, 6.0

SUMMARY

The sample code below illustrates how to use the for_each, begin, and end STL function in Visual C++.

MORE INFORMATION

Required Header


   <algorithm>

Prototype


   template<class InputIterator, class Function> inline

       Function for_each(InputIterator first,
                         InputIterator last,
                         Function F)

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 for_each algorithm calls Function F for each element in the range [first, last) and returns the input parameter F. This function does not modify any elements in the sequence.

Sample Code


////////////////////////////////////////////////////////////////////// 
// 
// Compile options needed: /GX
// 
// count.cpp : Illustrates how to use the for_each function.
// 
// Functions:
// 
//   for_each  - Calls function F for every element in a range.
// 
//   begin     - Returns an iterator that points to the first element
//               in a sequence.
// 
//   end       - Returns an iterator that points one past the end of
//               a sequence.
// 
// Written by Kalindi Sanghrajka
// of Microsoft Product Support Services,
// Software Core Developer Support.
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
////////////////////////////////////////////////////////////////////// 

// disable warning C4786: symbol greater than 255 character,
// okay to ignore

#pragma warning(disable: 4786)

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

#if _MSC_VER > 1020   // if VC++ version is > 4.2
   using namespace std;  // std c++ libs implemented in std
   #endif

// prints the cube of integer n
void PrintCube(int n)

{

    cout << n * n * n << " " ;

}

void main()

{

    const int VECTOR_SIZE = 8 ;

    // Define a template class vector of integers
    typedef vector<int, allocator<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 ;

    int i ;

    // Initialize vector Numbers
    for (i = 0; i < VECTOR_SIZE; i++)
        Numbers[i] = i + 1 ;

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

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

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

    // for each element in the range [first, last)
    // print the cube of the element
    for_each(start, end, PrintCube) ;
    cout << "\n\n" ;

}

Output:


Numbers { 1 2 3 4 5 6 7 8  }

1 8 27 64 125 216 343 512

REFERENCES

Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.

Additional query words: STL STLSample for_each begin end

Keywords : kbcode kbVC420 kbVC500 kbVC600 kbDSupport STLIss
Version : winnt:4.2,5.0,6.0
Platform : winnt
Issue type : kbinfo