Standard C++ LibraryCopyright 1996, Rogue Wave Software, Inc.

NAME

  transform  - Applies an operation to a range of values in a collection and
  stores the result.

SYNOPSIS

  #include <algorithm>

  template <class InputIterator,
           class OutputIterator,
           class UnaryOperation>
  OutputIterator transform (InputIterator first,
                           InputIterator last,
                           OutputIterator result,
                           UnaryOperation op);

  template <class InputIterator1,
           class InputIterator2,
           class OutputIterator,
           class BinaryOperation>
  OutputIterator transform (InputIterator1 first1,
                           InputIterator1 last1,
                           InputIterator2 first2,
                           OutputIterator result,
                           BinaryOperation binary_op);

DESCRIPTION

  The transform algorithm has two forms.  The first form applies unary
  operation op to each element of the range [first, last), and sends the
  result to the output iterator result.  For example, this version of
  transform, could be used to square each element in a vector.  If the output
  iterator (result) is the same as the input iterator used to traverse the
  range, transform, performs its transformation in place.

  The second form of transform applies a binary operation, binary_op, to
  corresponding elements in the range [first1, last1) and the range that
  begins at first2, and sends the result to result.   For example, transform
  can be used to add corresponding elements in two sequences, and store the
  set of sums in a third.  The algorithm assumes, but does not check, that
  the second sequence has at least as many elements as the first sequence.
  Note that the output iterator result can be a third sequence, or either of
  the two input sequences.

  Formally, transform assigns through every  iterator i in the range [result,
  result + (last1 - first1)) a new corresponding value equal to:

  op(*(first1 + (i - result))

   or

  binary_op(*(first1 + (i - result), *(first2 + (i - result)))

  transform returns  result + (last1 - first1).   op and binary_op must not
  have any side effects.  result may be equal to first in case of unary
  transform, or to first1 or first2 in case of binary transform.

COMPLEXITY

  Exactly last1 - first1 applications of op or  binary_op  are performed.

EXAMPLE

  //
  // trnsform.cpp
  //
   #include <functional>
   #include <deque>
   #include <algorithm>
   #include <iostream.h>
   #include <iomanip.h>
  int main()
   {
     //Initialize a deque with an array of ints
    int arr1[5] = {99, 264, 126, 330, 132};
    int arr2[5] = {280, 105, 220, 84, 210};
    deque<int> d1(arr1, arr1+5), d2(arr2, arr2+5);
     //Print the original values
    cout << "The following pairs of numbers: "
          << endl << "     ";
    deque<int>::iterator i1;
    for(i1 = d1.begin(); i1 != d1.end(); i1++)
       cout << setw(6) << *i1 << " ";
    cout << endl << "     ";
    for(i1 = d2.begin(); i1 != d2.end(); i1++)
       cout << setw(6) << *i1 << " ";
     // Transform the numbers in the deque to their
     // factorials and store in the vector
     transform(d1.begin(), d1.end(), d2.begin(),
              d1.begin(), multiplies<int>());
     //Display the results
    cout << endl << endl;
    cout << "Have the products: " << endl << "     ";
    for(i1 = d1.begin(); i1 != d1.end(); i1++)
      cout << setw(6) << *i1 << " ";
    return 0;
   }

  Output :
  The following pairs of numbers:
          99    264    126    330    132
         280    105    220     84    210
  Have the products:
       27720  27720  27720  27720  27720

WARNING

  If your compiler does not support default template parameters, then you
  need to always supply the Allocator template argument.  For instance, you
  will need to write :

  deque<int, allocator<int> >

  instead of:

  deque<int>

STANDARDS CONFORMANCE

  ANSI X3J16/ISO WG21 Joint C++ Committee



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