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ae46f916f1
(https://github.com/ruby/stringio/pull/197) Previous doc merely linked to `IO#read`; new doc stays local, shows examples using `StringIO`. https://github.com/ruby/stringio/commit/e8b66f8cdd
84 lines
2.8 KiB
Plaintext
84 lines
2.8 KiB
Plaintext
Reads and returns a string containing bytes read from the stream,
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beginning at the current position;
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advances the position by the count of bytes read.
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With no arguments given,
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reads all remaining bytes in the stream;
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returns a new string containing bytes read:
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strio = StringIO.new('Hello') # Five 1-byte characters.
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strio.read # => "Hello"
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strio.pos # => 5
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strio.read # => ""
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StringIO.new('').read # => ""
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With non-negative argument +maxlen+ given,
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reads +maxlen+ bytes as available;
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returns a new string containing the bytes read, or +nil+ if none:
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strio.rewind
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strio.read(3) # => "Hel"
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strio.read(3) # => "lo"
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strio.read(3) # => nil
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russian = 'Привет' # Six 2-byte characters.
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russian.b
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# => "\xD0\x9F\xD1\x80\xD0\xB8\xD0\xB2\xD0\xB5\xD1\x82"
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strio = StringIO.new(russian)
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strio.read(6) # => "\xD0\x9F\xD1\x80\xD0\xB8"
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strio.read(6) # => "\xD0\xB2\xD0\xB5\xD1\x82"
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strio.read(6) # => nil
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japanese = 'こんにちは'
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japanese.b
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# => "\xE3\x81\x93\xE3\x82\x93\xE3\x81\xAB\xE3\x81\xA1\xE3\x81\xAF"
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strio = StringIO.new(japanese)
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strio.read(9) # => "\xE3\x81\x93\xE3\x82\x93\xE3\x81\xAB"
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strio.read(9) # => "\xE3\x81\xA1\xE3\x81\xAF"
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strio.read(9) # => nil
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With argument +max_len+ as +nil+ and string argument +out_string+ given,
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reads the remaining bytes in the stream;
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clears +out_string+ and writes the bytes into it;
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returns +out_string+:
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out_string = 'Will be overwritten'
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strio = StringIO.new('Hello')
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strio.read(nil, out_string) # => "Hello"
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strio.read(nil, out_string) # => ""
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With non-negative argument +maxlen+ and string argument +out_string+ given,
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reads the +maxlen bytes from the stream, as availble;
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clears +out_string+ and writes the bytes into it;
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returns +out_string+ if any bytes were read, or +nil+ if none:
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out_string = 'Will be overwritten'
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strio = StringIO.new('Hello')
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strio.read(3, out_string) # => "Hel"
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strio.read(3, out_string) # => "lo"
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strio.read(3, out_string) # => nil
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out_string = 'Will be overwritten'
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strio = StringIO.new(russian)
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strio.read(6, out_string) # => "При"
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strio.read(6, out_string) # => "вет"
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strio.read(6, out_string) # => nil
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strio.rewind
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russian.b
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# => "\xD0\x9F\xD1\x80\xD0\xB8\xD0\xB2\xD0\xB5\xD1\x82"
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strio.read(3) # => "\xD0\x9F\xD1"
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strio.read(3) # => "\x80\xD0\xB8"
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out_string = 'Will be overwritten'
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strio = StringIO.new(japanese)
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strio.read(9, out_string) # => "こんに"
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strio.read(9, out_string) # => "ちは"
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strio.read(9, out_string) # => nil
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strio.rewind
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japanese.b
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# => "\xE3\x81\x93\xE3\x82\x93\xE3\x81\xAB\xE3\x81\xA1\xE3\x81\xAF"
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strio.read(4) # => "\xE3\x81\x93\xE3"
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strio.read(4) # => "\x82\x93\xE3\x81"
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Related: #gets, #readlines.
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