Q156079: STL Sample for the Generate Function

Article: Q156079
Product(s): Microsoft C Compiler
Version(s): winnt:4.2
Operating System(s): 
Keyword(s): _IK
Last Modified: 07-MAY-2001

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The information in this article applies to:

- The Standard C++ Library, included with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
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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>
  using namespace std;
  // 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          : _IK 
Technology        : kbVCsearch kbAudDeveloper kbVCLibrary
Version           : winnt:4.2
Issue type        : kbhowto

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