---
name: "ranger"
section: "3bobcat"
platform: "linux"
package: "libbobcat-dev"
version: "6.07.01-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/ranger/3bobcat"
---

# ranger(3bobcat)

generalizes ranges for range-based for-loops

## 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.

- o

  **Ranger\<Iterator\> ranger(Iterator &&begin, Iterator &&end)**:\
   this function template returns a *Ranger* object for the (sub)range defined by two (reverse) iterators;

- o

  **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*;

- o

  **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*;

- o

  **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 \**).

- o

  **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

- o

  **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.

- o

  **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)](/bobcat/7.md), [**reverse**(3bobcat)](/reverse/3bobcat.md)

## BUGS

None Reported.

## BOBCAT PROJECT FILES

- o

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

Debian Bobcat project files:

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  *libbobcat6*: debian package containing the shared library, changelog and copyright note;

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  *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**).