---
name: "struct_set"
section: "3tcl"
platform: "linux"
package: "tcllib"
version: "2.0+dfsg-4"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/struct_set"
---

# struct\_set(3tcl)

Procedures for manipulating sets

```

```

## NAME

struct::set - Procedures for manipulating sets

## SYNOPSIS

package require **Tcl 8.5 9**

package require **struct::set ?2.2.4?**

**::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.

When proposing code changes, please provide *unified diffs*, i.e the output of **diff -u**.

Note further that *attachments* are strongly preferred over inlined patches. Attachments can be made by going to the **Edit** form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.

## KEYWORDS

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

## CATEGORY

Data structures

## COPYRIGHT

```
Copyright (c) 2004-2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>
```