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instance method

String#unpack1

str.unpack1(format) → obj

# File tmp/rubies/ruby-3.0.5/pack.rb, line 280
def unpack1(fmt)
  Primitive.pack_unpack1(fmt)
end

Decodes str (which may contain binary data) according to the format string, returning the first value extracted. See also String#unpack, Array#pack.

Contrast with String#unpack:

Example

"abc \0\0abc \0\0".unpack('A6Z6')   #=> ["abc", "abc "]
"abc \0\0abc \0\0".unpack1('A6Z6')  #=> "abc"

In that case data would be lost but often it’s the case that the array only holds one value, especially when unpacking binary data. For instance:

“\xff\x00\x00\x00”.unpack(“l”) #=> [255] “\xff\x00\x00\x00”.unpack1(“l”) #=> 255

Thus unpack1 is convenient, makes clear the intention and signals the expected return value to those reading the code.

See also #unpack #upcase #unicode_normalized? #upcase! also in 4.1 · 4.0 · 3.4 · 3.3 · 3.2 · 3.1

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