Converting string characters to or from their integer value (7-bit ASCII value or UTF-8 codepoint) can be done in different ways in Ruby:
-
String#ordorString#unpackto get character values -
Integer#chrorArray#packto convert character values into Strings
Character values to Strings
Integer#chr
To get the character for a 7-bit ASCII value or UTF-8 codepoint (0-127) you can use Integer#chr:
116.chr
# => "t"
To get a character for values larger than 127, you need to pass the encoding. E.g. to get codepoint 252 in UTF-8:
252.chr(Encoding::UTF_8)
# => "ü"
Array#pack
pack may feel less intuitive, but does not require passing an encoding option. You need the U* directive.
[116].pack('U*')
# => "t"
[252].pack('U*')
# => "ü"
Note that you must wrap your value numbers into an Array. In turn, this allows constructing Strings from multiple values easily:
[116, 252, 114, 32, 9786].pack('U*')
# => "tür ☺"
Note that the asterisk (*) is required for strings longer than 1 character.
Strings to character values
String#ord
To convert back from a String to its codepoint, use String#ord:
"t".ord
# => 116
String#unpack
Strings offer unpack as an inverse to Array#pack. Codepoints will be returned as arrays, and you can convert entire strings:
"t".unpack('U*')
# => [106]
"tür ☺".unpack('U*')
# => [116, 252, 114, 32, 9786]
pack/unpack can also convert into many other values or encodings (like quoted-printable). Please see
the pack documentation
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for more information.
