Preview Ruby 4.1 is a preview. It can change before the final release. Switch to Ruby 4.0 →

instance method

String#unpack1

(::string template, ?offset: ::int) -> (::Integer | ::Float | ::String)?

unpack1(template, offset: 0) → object

# File tmp/rubies/ruby-4.1.0-preview1/pack.rb, line 37
def unpack1(fmt, offset: 0)
  Primitive.pack_unpack1(fmt, offset)
end

Like String#unpack with no block, but unpacks and returns only the first extracted object. See Packed Data.

Ruby version changes

4.1
- String#unpack and String#unpack1 accept new formats R and r for unsigned and signed LEB128 encoded integers. [Feature #21785]
- String#unpack and String#unpack1 accept a new format ^ that returns the current offset. Useful when combined with variable width formats like LEB128. [Feature #21796]
- String#unpack and String#unpack1 accept new formats x! and @! to align the current offset to a byte boundary or to the ABI alignment of another directive. [Feature #22185]
3.1
- String#unpack and String#unpack1 now accept an offset: keyword argument to start the unpacking after an arbitrary number of bytes have been skipped. If offset is outside of the string bounds ArgumentError is raised. [Feature #18254]

See also #unpack #upcase #unicode_normalized? #upcase! also in 4.0 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0