File: counting_iterator_eg.rst

package info (click to toggle)
boost 1.32.0-6
  • links: PTS
  • area: main
  • in suites: sarge
  • size: 93,952 kB
  • ctags: 128,458
  • sloc: cpp: 492,477; xml: 52,125; python: 13,519; ansic: 13,013; sh: 1,773; yacc: 853; makefile: 526; perl: 418; lex: 110; csh: 6
file content (40 lines) | stat: -rw-r--r-- 1,211 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

Example
.......

This example fills an array with numbers and a second array with
pointers into the first array, using ``counting_iterator`` for both
tasks. Finally ``indirect_iterator`` is used to print out the numbers
into the first array via indirection through the second array.

::

    int N = 7;
    std::vector<int> numbers;
    typedef std::vector<int>::iterator n_iter;
    std::copy(boost::counting_iterator<int>(0),
             boost::counting_iterator<int>(N),
             std::back_inserter(numbers));

    std::vector<std::vector<int>::iterator> pointers;
    std::copy(boost::make_counting_iterator(numbers.begin()),
	      boost::make_counting_iterator(numbers.end()),
	      std::back_inserter(pointers));

    std::cout << "indirectly printing out the numbers from 0 to " 
	      << N << std::endl;
    std::copy(boost::make_indirect_iterator(pointers.begin()),
	      boost::make_indirect_iterator(pointers.end()),
	      std::ostream_iterator<int>(std::cout, " "));
    std::cout << std::endl;


The output is::

    indirectly printing out the numbers from 0 to 7
    0 1 2 3 4 5 6 

The source code for this example can be found `here`__.

__ ../example/counting_iterator_example.cpp