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humanize_number(3) [freebsd man page]

HUMANIZE_NUMBER(3)					   BSD Library Functions Manual 					HUMANIZE_NUMBER(3)

NAME
humanize_number -- format a number into a human readable form LIBRARY
System Utilities Library (libutil, -lutil) SYNOPSIS
#include <libutil.h> int humanize_number(char *buf, size_t len, int64_t number, const char *suffix, int scale, int flags); DESCRIPTION
The humanize_number() function formats the signed 64-bit quantity given in number into buf. A space and then suffix is appended to the end. The buffer pointed to by buf must be at least len bytes long. If the formatted number (including suffix) would be too long to fit into buf, then divide number by 1024 until it will. In this case, prefix suffix with the appropriate designator. The humanize_number() function follows the traditional computer science conventions by default, rather than the IEE/IEC (and now also SI) power of two convention or the power of ten notion. This behaviour however can be altered by spec- ifying the HN_DIVISOR_1000 and HN_IEC_PREFIXES flags. The traditional (default) prefixes are: Prefix Description Multiplier Multiplier 1000x (note) kilo 1024 1000 M mega 1048576 1000000 G giga 1073741824 1000000000 T tera 1099511627776 1000000000000 P peta 1125899906842624 1000000000000000 E exa 1152921504606846976 1000000000000000000 Note: An uppercase K indicates a power of two, a lowercase k a power of ten. The IEE/IEC (and now also SI) power of two prefixes are: Prefix Description Multiplier Ki kibi 1024 Mi mebi 1048576 Gi gibi 1073741824 Ti tebi 1099511627776 Pi pebi 1125899906842624 Ei exbi 1152921504606846976 The len argument must be at least 4 plus the length of suffix, in order to ensure a useful result is generated into buf. To use a specific prefix, specify this as scale (multiplier = 1024 ^ scale; when HN_DIVISOR_1000 is specified, multiplier = 1000 ^ scale). This cannot be com- bined with any of the scale flags below. The following flags may be passed in scale: HN_AUTOSCALE Format the buffer using the lowest multiplier possible. HN_GETSCALE Return the prefix index number (the number of times number must be divided to fit) instead of formatting it to the buffer. The following flags may be passed in flags: HN_DECIMAL If the final result is less than 10, display it using one decimal place. HN_NOSPACE Do not put a space between number and the prefix. HN_B Use 'B' (bytes) as prefix if the original result does not have a prefix. HN_DIVISOR_1000 Divide number with 1000 instead of 1024. HN_IEC_PREFIXES Use the IEE/IEC notion of prefixes (Ki, Mi, Gi...). This flag has no effect when HN_DIVISOR_1000 is also specified. RETURN VALUES
Upon success, the humanize_number function returns the number of characters that would have been stored in buf (excluding the terminating NUL) if buf was large enough, or -1 upon failure. Even upon failure, the contents of buf may be modified. If HN_GETSCALE is specified, the prefix index number will be returned instead. SEE ALSO
expand_number(3) STANDARDS
The HN_DIVISOR_1000 and HN_IEC_PREFIXES flags conform to ISO/IEC Std 80000-13:2008 and IEEE Std 1541-2002. HISTORY
The humanize_number() function first appeared in NetBSD 2.0 and then in FreeBSD 5.3. The HN_IEC_PREFIXES flag was introduced in FreeBSD 9.0. BSD
October 7, 2013 BSD

Check Out this Related Man Page

UNITS(7)						     Linux Programmer's Manual							  UNITS(7)

NAME
units, kilo, kibi, mega, mebi, giga, gibi - decimal and binary prefixes DESCRIPTION
Decimal prefixes The SI system of units uses prefixes that indicate powers of ten. A kilometer is 1000 meter, and a megawatt is 1000000 watt. Below the standard prefixes. Prefix Name Value y yocto 10^-24 = 0.000000000000000000000001 z zepto 10^-21 = 0.000000000000000000001 a atto 10^-18 = 0.000000000000000001 f femto 10^-15 = 0.000000000000001 p pico 10^-12 = 0.000000000001 n nano 10^-9 = 0.000000001 u micro 10^-6 = 0.000001 m milli 10^-3 = 0.001 c centi 10^-2 = 0.01 d deci 10^-1 = 0.1 da deka 10^ 1 = 10 h hecto 10^ 2 = 100 k kilo 10^ 3 = 1000 M mega 10^ 6 = 1000000 G giga 10^ 9 = 1000000000 T tera 10^12 = 1000000000000 P peta 10^15 = 1000000000000000 E exa 10^18 = 1000000000000000000 Z zetta 10^21 = 1000000000000000000000 Y yotta 10^24 = 1000000000000000000000000 The symbol for micro is the Greek letter mu, often written u in an ASCII context where this Greek letter is not available. See also http://physics.nist.gov/cuu/Units/prefixes.html Binary prefixes The binary prefixes resemble the decimal ones, but have an additional 'i' (and "Ki" starts with a capital 'K'). The names are formed by taking the first syllable of the names of the decimal prefix with roughly the same size, followed by "bi" for "binary". Prefix Name Value Ki kibi 2^10 = 1024 Mi mebi 2^20 = 1048576 Gi gibi 2^30 = 1073741824 Ti tebi 2^40 = 1099511627776 Pi pebi 2^50 = 1125899906842624 Ei exbi 2^60 = 1152921504606846976 See also http://physics.nist.gov/cuu/Units/binary.html Discussion Before these binary prefixes were introduced, it was fairly common to use k=1000 and K=1024, just like b=bit, B=byte. Unfortunately, the M is capital already, and cannot be capitalized to indicate binary-ness. At first that didn't matter too much, since memory modules and disks came in sizes that were powers of two, so everyone knew that in such contexts "kilobyte" and "megabyte" meant 1024 and 1048576 bytes, respectively. What originally was a sloppy use of the prefixes "kilo" and "mega" started to become regarded as the "real true meaning" when computers were involved. But then disk technology changed, and disk sizes became arbitrary numbers. After a period of uncertainty all disk manufacturers settled on the standard, namely k=1000, M=1000k, G=1000M. The situation was messy: in the 14k4 modems, k=1000; in the 1.44MB diskettes, M=1024000; etc. In 1998 the IEC approved the standard that defines the binary prefixes given above, enabling people to be precise and unambiguous. Thus, today, MB = 1000000B and MiB = 1048576B. In the free software world programs are slowly being changed to conform. When the Linux kernel boots and says hda: 120064896 sectors (61473 MB) w/2048KiB Cache the MB are megabytes and the KiB are kibibytes. Linux 2001-12-22 UNITS(7)
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