STL Sample for the for_each Function

• The Standard C++ Library included with: - Microsoft Visual C++, 32-bit Edition, version 4.2

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)

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

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

// 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.