CGAL 4.7 - Geometric Object Generators: CGAL::Combination_enumerator< CombinationElement > Class Template Reference

\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)

CGAL 4.7 - Geometric Object Generators

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CGAL::Combination_enumerator< CombinationElement > Class Template Reference
Geometric Object Generators Reference

`#include <CGAL/Combination_enumerator.h>`

## Definition

The class `Combination_enumerator` is used to enumerate all fixed-size combinations (subsets) of a source range of elements.

For example, it can enumerate all the combinations of 2 elements from the source range `[3,7)` (`7` excluded) which gives the enumeration `{3,4}, {3,5}, {3,6}, {4,5}, {4,6}, {5,6}`. The source range consists of elements of type `CombinationElement` and is specified by its first element and the element just beyond its last one.

Template Parameters

  CombinationElement | should be a model of the concept `CombinationElement`.

Each combination is uniquely represented as an increasing sequence of elements. Thus, the combinations can be lexicographically ordered. They are enumerated in that order, so that we can talk about the first or last combination.

Examples:
  Generator/combination_enumerator.cpp, and Generator/name_pairs.cpp.

## Creation

| Combination_enumerator (int k, const CombinationElement &first, const CombinationElement &beyond)
| This constructor initializes the object to enumerate the combinations of `k` elements from the source range `[first, beyond)`. More...
| Combination_enumerator (const Combination_enumerator &combi)
| The copy constructor.

## Access to the Current Combination

const CombinationElement & | operator[] (int i)
| Returns the `i`-th element of the current combination. More...

## Access to the Enumeration

int | number_of_elements ()
| Returns the size of the enumerated combinations (the parameter `k` from the class' constructor).
const CombinationElement & | min_element ()
| Returns the smallest element of the source range. More...
const CombinationElement & | beyond_element ()
| Returns the successor to the largest element of the source range (the parameter `beyond` of the constructor of the class).
bool | finished ()
| Returns `true` if and only if all combinations have been enumerated.

## Operations

void | reset ()
| Resets the enumerator. More...
void | operator++ ()
| Moves *this to the next combination.
Combination_enumerator | operator++ (int)
| Post-incrementation. More...