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

     humanize_number --	format a number	into a human readable form

     System Utilities Library (libutil,	-lutil)

     #include <libutil.h>

     humanize_number(char *buf,	size_t len, int64_t number,
	 const char *suffix, int scale,	int flags);

     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 specifying 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

     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 pre-
     fix, specify this as scale	(multiplier = 1024 ^ scale; when
     HN_DIVISOR_1000 is	specified, multiplier =	1000 ^ scale).	This cannot be
     combined with any of the scale flags below.

     The following flags may be	passed in scale:

	   HN_AUTOSCALE	    Format the buffer using the	lowest multiplier pos-

	   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.

     Upon success, the humanize_number function	returns	the number of charac-
     ters that would have been stored in buf (excluding	the terminating	NUL)
     if	buf was	large enough, or -1 upon failure.  Even	upon failure, the con-
     tents of buf may be modified.  If HN_GETSCALE is specified, the prefix
     index number will be returned instead.


     The HN_DIVISOR_1000 and HN_IEC_PREFIXES flags conform to ISO/IEC
     Std 80000-13:2008 and IEEE	Std 1541-2002.

     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.

     For numbers greater than 999 using	buffer length of 4 and less can	cause
     rounding errors.  When using HN_IEC_PREFIXES the same error occurs	for
     buffer length of 5	or less.

BSD				October	7, 2013				   BSD


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