HUMANIZE_NUMBER(3)

NAME
dehumanize_number, humanize_number - format a number into a human readable form and vice versa

SYNOPSIS
#include <stdlib.h>
int
dehumanize_number(const char *str, int64_t *result);
int
humanize_number(char *buffer, 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 buffer. A space and then the suffix (if not null) is appended to the end. len gives the size of the buffer.

If the formatted number (including suffix) would be too long to fit into buffer, then repeatedly divide number by 1024 until it will fit. In this case, prefix suffix with the appropriate SI designator.

The prefixes are:
Prefix | Description | Multiplier
k kilo 1024
M mega 1048576
G giga 1073741824
T tera 1099511627776
P peta 1125899906842624
E exa 1152921504606846976

len must be at least 4 plus the length of suffix, in order to ensure a useful result is generated into buffer. To use a specific prefix, specify this as scale (Multiplier = 1024 ^ scale). The scale must be at least 0 and no more than 6.

Alternatively, one of the following special values may be given as 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. That is, the scale that would have been used if HN_AUTOSCALE had been used.

The following flags may be passed in flags:

HN_DECIMAL
    If the final numeric result is less than 10, and is not the same as the original value (that is, it has been scaled) display it using a decimal radix character, and one following digit.

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. That is, use decimal scaling instead of binary.

To generate the shortest meaningful value, a buffer length (len) that is 6 greater the length of the suffix along with HN_AUTOSCALE will ensure the highest meaningful scale is used. Allow one extra byte for the sign if the number is negative, and one less if the HN_NOSPACE flag is used.

The dehumanize_number() function parses the string representing an integral value given in str and stores the numerical value in the integer pointed to by result. The provided string may hold one of the suffixes, which will be interpreted and used to scale up its accompanying numerical value.

RETURN VALUES
humanize_number() returns the number of characters stored in buffer (excluding the terminating NUL) upon success, or -1 upon failure. If HN_GETSCALE is specified, the prefix index number will be returned instead.

dehumanize_number() returns 0 if the string was parsed correctly. A -1 is returned to indicate failure and an error code is stored in errno.

ERRORS
dehumanize_number() will fail and no number will be stored in result if:

[EINVAL]
    The string in str was empty or carried an unknown suffix.

[ERANGE]
    The string in str represented a number that does not fit in result.

SEE ALSO
strsuftoll(3), orders(7), humanize_number(9)

HISTORY
humanize_number() first appeared in NetBSD 2.0.

dehumanize_number() first appeared in NetBSD 5.0.