Man Page for_each.3

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

NAME

     for_each

      - Applies a function to each element in a range.

SYNOPSIS

     #include <algorithm>
     template <class InputIterator, class Function>
     void for_each(InputIterator first, InputIterator last,
                   Function f);

DESCRIPTION

     The for_each algorithm applies function f to all members  of
     the  sequence  in  the  range [first, last), where first and
     last are iterators that define the sequence.  Since  this  a
     non-mutating  algorithm,  the  function  f  cannot  make any
     modifications to the sequence, but it  can  achieve  results
     through  side  effects  (such  as copying or printing). If f
     returns a result, the result is ignored.

COMPLEXITY

     The function f is applied exactly last - first times.

EXAMPLE

     //
     // for_each.cpp
     //
     #include <vector>
     #include <algorithm>
     #include <functional>
     #include <iostream>
     using namespace std;

      // Function class that outputs its argument times x
     template <class Arg>
     class out_times_x :  private unary_function<Arg,void>
      {
       private:
          Arg multiplier;

       public:
          out_times_x(const Arg& x) : multiplier(x) { }
          void operator()(const Arg& x)
              { cout << x * multiplier << " " << endl; }
      };

     int main()
      {
       int sequence[5] = {1,2,3,4,5};


        // Set up a vector
       vector<int> v(sequence,sequence + 5);


        // Setup a function object
       out_times_x<int> f2(2);

        for_each(v.begin(),v.end(),f2);   // Apply function

       return 0;
      }

     Program Output




     2
     4
     6
     8
     10

WARNINGS

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

     Algorithms, Function_Objects