Getting accurate file size in megabytes?

Question

How can I get the accurate file size in MB? I tried this:

compressed_file_size = File.size("Compressed/#{project}.tar.bz2") / 1024000  puts "file size is #{compressed_file_size} MB" 

But it chopped the 0.9 and showed 2 MB instead of 2.9 MB

Answer 1

Try:

compressed_file_size = File.size("Compressed/#{project}.tar.bz2").to_f / 2**20 formatted_file_size = '%.2f' % compressed_file_size 

One-liner:

compressed_file_size = '%.2f' % (File.size("Compressed/#{project}.tar.bz2").to_f / 2**20) 

or:

compressed_file_size = (File.size("Compressed/#{project}.tar.bz2").to_f / 2**20).round(2) 

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Further information on %-operator of String: http://ruby-doc.org/core-1.9/classes/String.html#M000207

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BTW: I prefer "MiB" instead of "MB" if I use base2 calculations (see: http://en.wikipedia.org/wiki/Mebibyte)

Answer 2

You're doing integer division (which drops the fractional part). Try dividing by 1024000.0 so ruby knows you want to do floating point math.