FAQ 9.18 How do I decode a MIME/BASE64 string?

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9.18: How do I decode a MIME/BASE64 string?

The "MIME-Base64" package (available from CPAN) handles this as well as
the MIME/QP encoding. Decoding BASE64 becomes as simple as:

use MIME::Base64;
$decoded = decode_base64($encoded);

The "MIME-Tools" package (available from CPAN) supports extraction with
decoding of BASE64 encoded attachments and content directly from email
messages.

If the string to decode is short (less than 84 bytes long) a more direct
approach is to use the "unpack()" function's "u" format after minor
transliterations:

tr#A-Za-z0-9+/##cd; # remove non-base64 chars
tr#A-Za-z0-9+/# -_#; # convert to uuencoded format
$len = pack("c", 32 + 0.75*length); # compute length byte
print unpack("u", $len . $_); # uudecode and print



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