How to encode or decode quoted-printable strings

E-mails are usually encoded using Quoted Printable Show archive.org snapshot . Here is how to decode or encode such strings.

You probably know Quoted Printable from e-mail bodies appearing in Rails logs, where =s become =3Ds in URLs, or where long lines are split up and trailed by = after each split.

Decode Quoted Printable

Decoding such strings is actually quite simple using plain Ruby:

"foo=3Dbar".unpack('M')[0]
# => "foo=bar"

Note that unpack will return an array. Our result is the 1st item.

Encode a string as Quoted Printable

If you ever need to encode that manually, pack your input similarly:

["foo=bar"].pack('M')
# => "foo=3Dbar\n"

Note the extra line break, and that you need to wrap your input string into an array.