## SYNOPSIS

package require**Tcl 8.0**

package require **struct::set ?2.2.3?**

**::struct::set** **empty** *set*

**::struct::set** **size** *set*

**::struct::set** **contains** *set* *item*

**::struct::set** **union** ?*set1*...?

**::struct::set** **intersect** ?*set1*...?

**::struct::set** **difference** *set1* *set2*

**::struct::set** **symdiff** *set1* *set2*

**::struct::set** **intersect3** *set1* *set2*

**::struct::set** **equal** *set1* *set2*

**::struct::set** **include** *svar* *item*

**::struct::set** **exclude** *svar* *item*

**::struct::set** **add** *svar* *set*

**::struct::set** **subtract** *svar* *set*

**::struct::set** **subsetof** *A* *B*

## DESCRIPTION

The **::struct::set** namespace contains several useful commands for
processing finite sets.

It exports only a single command, **struct::set**. All
functionality provided here can be reached through a subcommand of
this command.

*Note:* As of version 2.2 of this package a critcl based C
implementation is available. This implementation however requires Tcl
8.4 to run.

## COMMANDS

**::struct::set****empty***set*-
Returns a boolean value indicating if the
*set*is empty (**true**), or not (**false**). **::struct::set****size***set*-
Returns an integer number greater than or equal to zero. This is the
number of elements in the
*set*. In other words, its cardinality. **::struct::set****contains***set**item*-
Returns a boolean value indicating if the
*set*contains the element*item*(**true**), or not (**false**). **::struct::set****union**?*set1*...?-
Computes the set containing the union of
*set1*,*set2*, etc., i.e. "*set1*+*set2*+ ...", and returns this set as the result of the command. **::struct::set****intersect**?*set1*...?-
Computes the set containing the intersection of
*set1*,*set2*, etc., i.e. "*set1***set2** ...", and returns this set as the result of the command. **::struct::set****difference***set1**set2*-
Computes the set containing the difference of
*set1*and*set2*, i.e. ("*set1*-*set2*") and returns this set as the result of the command. **::struct::set****symdiff***set1**set2*-
Computes the set containing the symmetric difference of
*set1*and*set2*, i.e. ("(*set1*-*set2*) + (*set2*-*set1*)") and returns this set as the result of the command. **::struct::set****intersect3***set1**set2*-
This command is a combination of the methods
**intersect**and**difference**. It returns a three-element list containing "*set1***set2*", "*set1*-*set2*", and "*set2*-*set1*", in this order. In other words, the intersection of the two parameter sets, and their differences. **::struct::set****equal***set1**set2*-
Returns a boolean value indicating if the two sets are equal
(
**true**) or not (**false**). **::struct::set****include***svar**item*-
The element
*item*is added to the set specified by the variable name in*svar*. The return value of the command is empty. This is the equivalent of**lappend**for sets. If the variable named by*svar*does not exist it will be created. **::struct::set****exclude***svar**item*-
The element
*item*is removed from the set specified by the variable name in*svar*. The return value of the command is empty. This is a near-equivalent of**lreplace**for sets. **::struct::set****add***svar**set*-
All the element of
*set*are added to the set specified by the variable name in*svar*. The return value of the command is empty. This is like the method**include**, but for the addition of a whole set. If the variable named by*svar*does not exist it will be created. **::struct::set****subtract***svar**set*-
All the element of
*set*are removed from the set specified by the variable name in*svar*. The return value of the command is empty. This is like the method**exclude**, but for the removal of a whole set. **::struct::set****subsetof***A**B*-
Returns a boolean value indicating if the set
*A*is a true subset of or equal to the set*B*(**true**), or not (**false**).

## REFERENCES

## BUGS, IDEAS, FEEDBACK

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category*struct :: set*of the

*Tcllib Trackers*[http://core.tcl.tk/tcllib/reportlist]. Please also report any ideas for enhancements you may have for either package and/or documentation.

## KEYWORDS

cardinality, difference, emptiness, exclusion, inclusion, intersection, membership, set, symmetric difference, union## CATEGORY

Data structures## COPYRIGHT

Copyright (c) 2004-2008 Andreas Kupries <[email protected]>