freebsd/lib/libutil/humanize_number.3

.\"	$NetBSD: humanize_number.3,v 1.4 2003/04/16 13:34:37 wiz Exp $
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.Dd May 25, 2004
.Dt HUMANIZE_NUMBER 3
.Os
.Sh NAME
.Nm humanize_number
.Nd format a number into a human readable form
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In libutil.h
.Ft int
.Fo humanize_number
.Fa "char *buf" "size_t len" "int64_t number" "const char *suffix"
.Fa "int scale" "int flags"
.Fc
.Sh DESCRIPTION
The
.Fn humanize_number
function formats the signed 64-bit quantity given in
.Fa number
into
.Fa buffer .
A space and then
.Fa suffix
is appended to the end.
The buffer pointed to by
.Fa buffer
must be at least
.Fa len
bytes long.
.Pp
If the formatted number (including
.Fa suffix )
would be too long to fit into
.Fa buffer ,
then divide
.Fa number
by 1024 until it will.
In this case, prefix
.Fa suffix
with the appropriate SI designator.
.Pp
The prefixes are:
.Bl -column "Prefix" "Description" "Multiplier" -offset indent
.It Sy "Prefix" Ta Sy "Description" Ta Sy "Multiplier"
.It Li k Ta No kilo Ta 1024
.It Li M Ta No mega Ta 1048576
.It Li G Ta No giga Ta 1073741824
.It Li T Ta No tera Ta 1099511627776
.It Li P Ta No peta Ta 1125899906842624
.It Li E Ta No exa Ta 1152921504606846976
.El
.Pp
The
.Fa len
argument must be at least 4 plus the length of
.Fa suffix ,
in order to ensure a useful result is generated into
.Fa buffer .
To use a specific prefix, specify this as
.Fa scale
(multiplier = 1024 ^ scale).
This cannot be combined with any of the
.Fa scale
flags below.
.Pp
The following flags may be passed in
.Fa scale :
.Bl -tag -width ".Dv HN_DIVISOR_1000" -offset indent
.It Dv HN_AUTOSCALE
Format the buffer using the lowest multiplier possible.
.It Dv HN_GETSCALE
Return the prefix index number (the number of times
.Fa number
must be divided to fit) instead of formatting it to the buffer.
.El
.Pp
The following flags may be passed in
.Fa flags :
.Bl -tag -width ".Dv HN_DIVISOR_1000" -offset indent
.It Dv HN_DECIMAL
If the final result is less than 10, display it using one digit.
.It Dv HN_NOSPACE
Do not put a space between
.Fa number
and the prefix.
.It Dv HN_B
Use
.Ql B
(bytes) as prefix if the original result does not have a prefix.
.It Dv HN_DIVISOR_1000
Divide
.Fa number
with 1000 instead of 1024.
.El
.Sh RETURN VALUES
The
.Fn humanize_number
function returns the number of characters stored in
.Fa buffer
(excluding the terminating
.Dv NUL )
upon success, or \-1 upon failure.
If
.Dv HN_GETSCALE
is specified, the prefix index number will be returned instead.
.Sh HISTORY
The
.Fn humanize_number
function first appeared in
.Nx 2.0 .