AMDG On 03/21/2018 03:01 AM, Simon Doppler via Boost-users wrote:

I am trying to build a program that will display file sizes in human readable form. The file size is in bytes and I am using boost::units to convert the bytes to a binary prefixed unit.

Using the example code found here[1], I build a small program to test the library and the output is off by a factor of 8:

boost::units::quantityboost::units::information::byte_base_unit::unit_type b = 2048. * boost::units::information::byte_base_unit::unit_type(); std::cout << boost::units::engineering_prefix << b << std::endl; // expected 2.048 kb std::cout << boost::units::symbol_format << boost::units::binary_prefix << b << std::endl; // "expected 2 Kib"

but the output on stdout is:

16.384 kb 16 Kib

which is 8 times the expected result. The whole example code can be found here[2].

The output is "correct" in some sense. The problem is that the output code is printing the value in terms of bits rather than bytes (note that it uses 'b' instead of 'B'). I'll see if I can solve this, but the formatting code is already pretty messy.

I have tested this code both on Archlinux (boost 1.66.0) as well as Ubuntu Xenial Server (libboost-dev 1.58.0.1ubuntu1).

Do you have any idea on how to get the correct output (other than divide the number of bytes by 8 on the input) ?

In Christ, Steven Watanabe