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

NAME

  replace_if  - Substitutes elements stored in a collection with new values.

SYNOPSIS

  #include <algorithm>

  template <class ForwardIterator,
           class Predicate,
           class T>
  void replace_if (ForwardIterator first,
                  ForwardIterator last,
                  Predicate pred
                  const T& new_value);

DESCRIPTION

  The replace_if algorithm replaces element referred to by iterator i in the
  range [first, last) with new_value when the following condition holds:
  pred(*i) == true.

COMPLEXITY

  Exactly last - first applications of the predicate are done.

EXAMPLE

  //
  // replace.cpp
  //
   #include <algorithm>
   #include <vector>
   #include <iterator>
   #include <iostream.h>

  template<class Arg>
  struct all_true : public unary_function<Arg, bool>
   {
    bool operator()(const Arg&){ return 1; }
   };

  int main()
   {

     //Initialize a vector with an array of integers
    int arr[10] = {1,2,3,4,5,6,7,8,9,10};
    vector<int> v(arr, arr+10);

     //Print out original vector
    cout << "The original list: " << endl << "     ";
    copy(v.begin(),v.end(),ostream_iterator<int,char>(cout," "));
    cout << endl << endl;

     //Replace the number 7 with 11
    replace(v.begin(), v.end(), 7, 11);

     // Print out vector with 7 replaced,
     // s.b. 1 2 3 4 5 6 11 8 9 10
    cout << "List after replace " << endl << "     ";
    copy(v.begin(),v.end(),ostream_iterator<int,char>(cout," "));
    cout << endl << endl;

     //Replace 1 2 3 with 13 13 13
     replace_if(v.begin(), v.begin()+3, all_true<int>(), 13);

     // Print out the remaining vector,
     // s.b. 13 13 13 4 5 6 11 8 9 10
    cout << "List after replace_if " << endl << "     ";
    copy(v.begin(),v.end(),ostream_iterator<int,char>(cout," "));
    cout << endl << endl;

    return 0;
   }

  Output :
  The original list:
      1 2 3 4 5 6 7 8 9 10
  List after replace:
      1 2 3 4 5 6 11 8 9 10
  List after replace_if:
      13 13 13 4 5 6 11 8 9 10
  List using replace_copy to cout:
      17 17 17 4 5 6 11 8 9 10
  List with all elements output as 19s:
      19 19 19 19 19 19 19 19 19 19

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 :

  vector<int, allocator<int> >

  instead of :

  vector<int>

SEE ALSO

  replace, replace_copy, replace_copy_if

STANDARDS CONFORMANCE

  ANSI X3J16/ISO WG21 Joint C++ Committee



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