# FBB::Ranger(3bobcat)

## for-loop iterators
(libbobcat-dev_6.07.01)

## 2005-2025

## NAME

FBB::Ranger - generalizes ranges for range-based for-loops

## SYNOPSIS

#include <bobcat/ranger>

## DESCRIPTION

The Ranger class template defines ranges that can be used with range-based for-loops. The standard range-based for-loop requires for its range-specificiation an array or an iterator range as offered by, e.g., containers (through their begin and end members). Ranges defined by a pair of pointers or by a subrange defined by iterator expressions cannot currently be used in combination with range-based for-loops.

Ranger extends the applicability of range-based for-loops by turning pairs of pointers, an initial pointer and a pointer count, or a pair of iterators into a range that can be used by range-based for-loops.

Ranger is a class template requiring one template type parameter: Iterator, an iterator or pointer type reaching the data when dereferenced.

Ranger's users don't have to specify Ranger's template type. The function template ranger returns the appropriate Ranger object.

## NAMESPACE

FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB.

## FREE FUNCTION

When using the following free functions, any (subrange) of iterators or pointers can be used. With iterators subranges of reverse iterators can also be specified. The EXAMPLE section below illustrates the use of the ranger function templates.

- Ranger<Iterator> ranger(Iterator &&begin, Iterator &&end):
  this function template returns a Ranger object for the (sub)range defined by two (reverse) iterators;
- Ranger<Iterator> ranger(Iterator &&begin, size_t count):
  this function template returns a Ranger object for the (sub)range defined by the (reverse) iterator range begin and begin + count;
- Ranger<Data *> ranger(Data *begin, Data *end):
  this function template returns a Ranger object for the (sub)range defined by the two pointers begin and end;
- Ranger<Data *> ranger(Data *begin, size_t count):
  this function template returns a Ranger object for the (sub)range defined by the two pointers begin and begin + count.

## CONSTRUCTORS

Below, Iterator refers to the Ranger class template's type parameter. Although named 'Iterator' it can also be a pointer to some data type (e.g., std::string *).

- Ranger(Iterator const &begin, Iterator const &end):
  A Ranger object can be passed as range-specifier in a range-based for-loop. All elements defined by the range will subsequently be visited by the range-based for-loop.

Copy and move constructors (and assignment operators) are available.

## MEMBER FUNCTIONS

- Iterator const &begin() const:
  returns (a copy of) the begin iterator passed to the Ranger's constructor. Note that if Iterator was a pointer type (like int *) the data to which the iterator returned by begin() can actually be modified, as the member's return type (using int * for Iterator) becomes int * const &, so a reference to a constant pointer to an int. This is perfectly OK: if the data themselves should be immutable, then the data type must be defined as int const, which is automatically the case when passing int const * data. See the EXAMPLE section for an illustration.
- Iterator const &end() const:
  returns (a copy of) the end iterator passed to the Ranger's constructor.

If reverse iterators are passed to Ranger's constructor, then the begin and end members return reverse iterators. Since the intended use of Ranger objects is to define a range for range-base for-loops, members like rbegin and rend can be omitted from Ranger.

## EXAMPLE

    #include <vector>
    #include <iostream>

    #include <bobcat/ranger>

    using namespace std;
    using namespace FBB;

    int main()
    {
        vector<int> iv {1, 2, 3, 4, 5};
                                        // display and modify a subrange
        for(auto &el: ranger(iv.rbegin() + 1, iv.rend() - 1))
            cout << el++ << ' ';
        cout << '\n';
                                        // display a reversed range
        for(auto &el: ranger(iv.rbegin() + 1, iv.rend() - 1))
            cout << el << ' ';
        cout << '\n';
                                        // same: display using a count
        for(auto &el: ranger(iv.rbegin() + 1, 3))
            cout << el << ' ';
        cout << '\n';

        int intArray[] = {1, 2, 3, 4, 5};
                                        // display and modify elements
                                        // in a pointer-based range
        for(auto &el: ranger(intArray + 1, intArray + 3))
            cout << el++ << ' ';
        cout << '\n';
                                        // data now modified
        for(auto &el: ranger(intArray + 1, intArray + 3))
            cout << el << ' ';
        cout << '\n';
                                        // using a count rather than an
                                        // end-pointer
        for(auto &el: ranger(intArray + 1, 3))
            cout << el << ' ';
        cout << '\n';

        int const constInts[] = {1, 2, 3, 4, 5};

                                        // data can't be modified
        for(auto &el: ranger(constInts + 1, constInts + 3))
            cout << el << ' ';
        cout << '\n';
    }

## FILES

bobcat/ranger - defines the class interface

## SEE ALSO

bobcat(7), reverse(3bobcat)

## BUGS

None Reported.

## BOBCAT PROJECT FILES

- https://fbb-git.gitlab.io/bobcat/: gitlab project page;

Debian Bobcat project files:

- libbobcat6: debian package containing the shared library, changelog and copyright note;
- libbobcat-dev: debian package containing the static library, headers, manual pages, and developer info;

## BOBCAT

Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.

## COPYRIGHT

This is free software, distributed under the terms of the GNU General Public License (GPL).

## AUTHOR

Frank B. Brokken (f.b.brokken@rug.nl).