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gawk: Extension Sample Read write array

 16.7.9 Dumping and Restoring an Array
 The 'rwarray' extension adds two functions, named 'writea()' and
 'reada()', as follows:
 '@load "rwarray"'
      This is how you load the extension.
 'ret = writea(file, array)'
      This function takes a string argument, which is the name of the
      file to which to dump the array, and the array itself as the second
      argument.  'writea()' understands arrays of arrays.  It returns one
      on success, or zero upon failure.
 'ret = reada(file, array)'
      'reada()' is the inverse of 'writea()'; it reads the file named as
      its first argument, filling in the array named as the second
      argument.  It clears the array first.  Here too, the return value
      is one on success, or zero upon failure.
    The array created by 'reada()' is identical to that written by
 'writea()' in the sense that the contents are the same.  However, due to
 implementation issues, the array traversal order of the re-created array
 is likely to be different from that of the original array.  As array
 traversal order in 'awk' is by default undefined, this is (technically)
 not a problem.  If you need to guarantee a particular traversal order,
 use the array sorting features in 'gawk' to do so (⇒Array
    The file contains binary data.  All integral values are written in
 network byte order.  However, double-precision floating-point values are
 written as native binary data.  Thus, arrays containing only string data
 can theoretically be dumped on systems with one byte order and restored
 on systems with a different one, but this has not been tried.
    Here is an example:
      @load "rwarray"
      ret = writea("arraydump.bin", array)
      ret = reada("arraydump.bin", array)
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