
[//000000001]: # (base64 \- Text encoding & decoding binary data)
[//000000002]: # (Generated from file 'base64\.man' by tcllib/doctools with format 'markdown')
[//000000003]: # (Copyright &copy; 2000, Eric Melski)
[//000000004]: # (Copyright &copy; 2001, Miguel Sofer)
[//000000005]: # (base64\(n\) 2\.6\.1 tcllib "Text encoding & decoding binary data")

<hr> [ <a href="../../../../toc.md">Main Table Of Contents</a> &#124; <a
href="../../../toc.md">Table Of Contents</a> &#124; <a
href="../../../../index.md">Keyword Index</a> &#124; <a
href="../../../../toc0.md">Categories</a> &#124; <a
href="../../../../toc1.md">Modules</a> &#124; <a
href="../../../../toc2.md">Applications</a> ] <hr>

# NAME

base64 \- base64\-encode/decode binary data

# <a name='toc'></a>Table Of Contents

  - [Table Of Contents](#toc)

  - [Synopsis](#synopsis)

  - [Description](#section1)

  - [Beware: Variations in decoding behaviour](#section2)

  - [API](#section3)

  - [Implementation Notes](#section4)

  - [EXAMPLES](#section5)

  - [Bugs, Ideas, Feedback](#section6)

  - [Keywords](#keywords)

  - [Category](#category)

  - [Copyright](#copyright)

# <a name='synopsis'></a>SYNOPSIS

package require Tcl 8\.5 9  
package require base64 ?2\.6\.1?  

[__::base64::encode__ ?__\-maxlen__ *maxlen*? ?__\-wrapchar__ *wrapchar*? *string*](#1)  
[__::base64::decode__ *string*](#2)  

# <a name='description'></a>DESCRIPTION

This package provides procedures to encode binary data into base64 and back\.

# <a name='section2'></a>Beware: Variations in decoding behaviour

The Tcl core provides since version 8\.6 commands for the de\- and encoding of
base64 data\. These are

    binary encode base64
    binary decode base64

Beware that while these are signature compatible with the commands provided by
this package, the decoders are *not behaviourally compatible*\.

The core decoder command accepts the option __\-strict__, enabling the user
to choose between strict and lax modes\. In the strict mode invalid characters,
and partial data at the end of the input are reported as errors\. In lax mode
they are ignored\.

All the implementations provided by this package on the other hand implement a
mix of the above, and the user cannot choose\. Partial data at the end of the
input is reported as error, and invalid characters are ignored\.

*Beware* of these differences when switching code from one to other\.

# <a name='section3'></a>API

  - <a name='1'></a>__::base64::encode__ ?__\-maxlen__ *maxlen*? ?__\-wrapchar__ *wrapchar*? *string*

    Base64 encodes the given binary *string* and returns the encoded result\.
    Inserts the character *wrapchar* every *maxlen* characters of output\.
    *wrapchar* defaults to newline\. *maxlen* defaults to __76__\.

    *Note* that if *maxlen* is set to __0__, the output will not be
    wrapped at all\.

    *Note well*: If your string is not simple ASCII you should fix the string
    encoding before doing base64 encoding\. See the examples\.

    The command will throw an error for negative values of *maxlen*, or if
    *maxlen* is not an integer number\.

  - <a name='2'></a>__::base64::decode__ *string*

    Base64 decodes the given *string* and returns the binary data\. The decoder
    ignores whitespace in the string\.

# <a name='section4'></a>Implementation Notes

This package contains three different implementations for base64 de\- and
encoding, and chooses among them based on the environment it finds itself in\.

All three implementations have the same behaviour\. See also [Beware: Variations
in decoding behaviour](#section2) at the beginning of this document\.

  1. If Tcl 8\.6 or higher is found the commands are implemented in terms of the
     then\-available builtin commands\.

  1. If the __Trf__ extension cand be loaded the commands are implemented in
     terms of its commands\.

  1. If neither of the above are possible a pure Tcl implementation is used\.
     This is of course much slower\.

# <a name='section5'></a>EXAMPLES

    % base64::encode "Hello, world"
    SGVsbG8sIHdvcmxk

    % base64::encode [string repeat xyz 20]
    eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6
    eHl6eHl6eHl6
    % base64::encode -wrapchar "" [string repeat xyz 20]
    eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6eHl6

    # NOTE: base64 encodes BINARY strings.
    % set chemical [encoding convertto utf-8 "C\u2088H\u2081\u2080N\u2084O\u2082"]
    % set encoded [base64::encode $chemical]
    Q+KCiEjigoHigoBO4oKET+KCgg==
    % set caffeine [encoding convertfrom utf-8 [base64::decode $encoded]]

# <a name='section6'></a>Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and
other problems\. Please report such in the category *base64* 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\.

# <a name='keywords'></a>KEYWORDS

[base64](\.\./\.\./\.\./\.\./index\.md\#base64),
[encoding](\.\./\.\./\.\./\.\./index\.md\#encoding)

# <a name='category'></a>CATEGORY

Text processing

# <a name='copyright'></a>COPYRIGHT

Copyright &copy; 2000, Eric Melski  
Copyright &copy; 2001, Miguel Sofer
