Issue #20614 has been updated by Eregon (Benoit Daloze). Agreed with @alanwu, the docs seems clear, and one would expect this method returns how many bytes are used to represent the Integer (not counting object header overhead for bignums, fair enough): ``` int.size -> int Document-method: Integer#size Returns the number of bytes in the machine representation of int (machine dependent). 1.size #=> 8 -1.size #=> 8 2147483647.size #=> 8 (256**10 - 1).size #=> 10 (256**20 - 1).size #=> 20 (256**40 - 1).size #=> 40 ``` So it should be pointer-size bytes for any Fixnum on any platform (since Fixnum are tagged pointers). ---------------------------------------- Bug #20614: Integer#size returns incorrect values on 64-bit Windows https://bugs.ruby-lang.org/issues/20614#change-109044 * Author: surusek (Łukasz Sur) * Status: Open * ruby -v: ruby 3.4.0dev (2024-07-08T11:00:01Z master 02c4f0c89d [x64-mswin64_140] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- According to the ruby/spec, `0.size` should return size of the machine word in bytes, but on x64-mswin64_140 (both release 3.3.3 and git revision 02c4f0c89d) it doesn't. Following example: ``` ruby a, b = 0.size, [0].pack('J').length puts a, b ``` should print two `8`s, but on x64-mswin64_140, a is `4`. Issue is most likely caused by use of `long` instead of `SIGNED_VALUE` in internal/fixnum.h and `fix_size` function in numeric.c, because on Windows, `long` is always a 32-bit number. -- https://bugs.ruby-lang.org/