iota is an STL algorithm since the C++0x standard, but used unofficially in earlier standards. This page describes the versions of iota:

iota for C++98

iota was not among the C++98 STL. Below the code shown an implementation and example of it.


#include <algorithm>

#include <iostream>

#include <iterator>

#include <numeric>

#include <vector>



// Numeric functions implementation -*- C++ -*-



// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009

// Free Software Foundation, Inc.

//

// This file is part of the GNU ISO C++ Library.  This library is free

// software; you can redistribute it and/or modify it under the

// terms of the GNU General Public License as published by the

// Free Software Foundation; either version 3, or (at your option)

// any later version.



// This library is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.



// Under Section 7 of GPL version 3, you are granted additional

// permissions described in the GCC Runtime Library Exception, version

// 3.1, as published by the Free Software Foundation.



// You should have received a copy of the GNU General Public License and

// a copy of the GCC Runtime Library Exception along with this program;

// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

// <http://www.gnu.org/licenses/>.



/*

 *

 * Copyright (c) 1994

 * Hewlett-Packard Company

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Hewlett-Packard Company makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 *

 *

 * Copyright (c) 1996,1997

 * Silicon Graphics Computer Systems, Inc.

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 */



/**

 *  @brief  Create a range of sequentially increasing values.

 *

 *  For each element in the range @p [first,last) assigns @p value and

 *  increments @p value as if by @p ++value.

 *

 *  @param  first  Start of range.

 *  @param  last  End of range.

 *  @param  value  Starting value.

 *  @return  Nothing.

 */

template<typename _ForwardIterator, typename _Tp>

  void iota(_ForwardIterator __first, _ForwardIterator __last, _Tp __value)

{

  // concept requirements

  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<

    _ForwardIterator>)

  __glibcxx_function_requires(_ConvertibleConcept<_Tp,

    typename iterator_traits<_ForwardIterator>::value_type>)

     __glibcxx_requires_valid_range(__first, __last);

  for (; __first != __last; ++__first)

  {

  *__first = __value;

  ++__value;

  }

}



int main()

{

  std::vector<int> v(10,0);



  iota(v.begin(),v.end(),0);



  std::copy(v.begin(),v.end(),std::ostream_iterator<int>(std::cout," "));

}

Screen output:


0 1 2 3 4 5 6 7 8 9

std::iota for C++0x

std::iota is in the C++0x STL and can be found in the header file algorithm.h.

Download the Qt Creator project 'CppIota' (zip)


#include <algorithm>

#include <iostream>

#include <iterator>

#include <vector>



int main()

{

  //Create a std::vector consisting of ten zeroes

  std::vector<int> v(10,0);



  //Let iota assign incrementing values to the std::vector,

  //starting from zero

  std::iota(v.begin(),v.end(),0);



  //Show the std::vector

  std::copy(v.begin(),v.end(),std::ostream_iterator<int>(std::cout," "));

}

Screen output:


0 1 2 3 4 5 6 7 8 9

Go back to Richel Bilderbeek's C++ page.

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(C++) iota, std::iota

iota for C++98

std::iota for C++0x