Man Page replace_if.3

                       Standard C++ Library
             Copyright 1998, Rogue Wave Software, Inc.

NAME

     replace_if

      - Substitutes elements 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>
     using namespace std;

     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;
      }

     Program 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

WARNINGS

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

     vector<int, allocator<int> >

     instead of:

     vector<int>

     If your compiler does not support namespaces,  then  you  do
     not need the using declaration for std.

SEE ALSO

     replace, replace_copy, replace_copy_if