STL Sample for the Generate Function

ID: Q156079

The information in this article applies to:

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

SUMMARY

The sample code below illustrates how to use the generate 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)
template<class ForwardIterator, class Generator> inline
 void generate(ForwardIterator first, ForwardIterator last, Generator gen)

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 Generate algorithm traverses the range [first, last + 1), assigning to each element the value returned by gen. Generate modifies the elements in the specified range.

Sample Code


////////////////////////////////////////////////////////////////////// 
// 
// Compile options needed: /GX
// 
// generate.cpp : Illustrates how to use the generate function.
// 
// Functions:
// 
//   generate - Fill a sequence using a generator function
//   Fibonacci - return the next Fibonacci number in the
//               Fibonacci series.
// 
// 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>
// return the next Fibonacci number in the
// Fibonacci series.
int Fibonacci(void)
{
    static int r;
    static int f1 = 0;
    static int f2 = 1;
    r = f1 + f2 ;
    f1 = f2 ;
    f2 = r ;
    return f1 ;
}
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 ;
    start = Numbers.begin() ;   // location of first
                                // element of Numbers
    end = Numbers.end() ;       // one past the location
                                // last element of Numbers
    // fill the range [first, last +1) with a series of
    // Fibonnaci numbers using the Fibonacci function
    generate(start, end, Fibonacci) ;
    // print content of Numbers
    cout << "Numbers { " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;
}

Program Output is:
Numbers { 1 1 2 3 5 8 13 21 }

REFERENCES

Visual C++ Books Online; click "Visual C++ Books," "C/C++," then "Standard C++ Library Reference."

Additional query words: STL generate

Keywords : kbcode STLIss
Version : WINNT:4.2;
Platform : NT WINDOWS
Issue type : kbhowto