fmt_scaled, scan_scaled - handle numbers with a human-readable scale
scan_scaled(char *number_w_scale, long long *result);
fmt_scaled(long long number, char *result);
The scan_scaled() function scans the given number and looks
for a terminal
scale multiplier of B, K, M, G, T, P or E (in either upper or lower
case) for Byte, Kilobyte, Megabyte, Gigabyte, Terabyte,
(computed using powers of two, i.e., Megabyte = 1024*1024).
can have a decimal point, as in 1.5K, which returns 1536
no scale factor is found, B is assumed.
The fmt_scaled() function formats a number for display using
"human-readable" format, that is, a number with one of the
factors. Numbers will be printed with a maximum of four
by a minus sign if the value is negative); values such as
1023B, 1K, 1.5K, 5.5M, and so on, will be generated. The
must be allocated with at least FMT_SCALED_STRSIZE bytes.
will be left-justified in the given space, and null-terminated.
The scan_scaled() and fmt_scaled() functions return 0 on
case of error, they return -1, leave *result as is, and set
errno to one
of the following values: EFAULT if an input pointer is NULL.
the input string represents a number that is too large to
EINVAL if an unknown character was used as scale factor, or
if the input
to scan_scaled() was malformed, e.g., too many '.' characters.
char *cinput = "1.5K";
long long result;
if (scan_scaled(cinput, &result) != 0)
printf("%s -> %ld0, cinput, result);
fprintf(stderr, "%s - invalid0, cinput);
long long ninput = 10483892;
if (fmt_scaled(ninput, buf) == 0)
printf("%lld -> %s0, ninput, buf);
fprintf(stderr, "fmt scaled failed (errno
The functions fmt_scaled() and scan_scaled() first appeared
Ken Stailey wrote the first version of the code that became
originally inside OpenBSD df(1). Ian Darwin excerpted this
and made it
into a library routine (with significant help from Paul
Some of the scale factors have misleading meanings in lower
case (p for P
is incorrect; p should be pico- and P for Peta-). However,
we bend the
SI rules in favor of common sense here. A person creating a
of "100m" is unlikely to require 100 millibytes (i.e.,
0.1 byte) of
storage in the partition; 100 megabytes is the only reasonable interpretation.
Cannot represent the larger scale factors on all architectures.
Ignores the current locale.
OpenBSD 3.6 September 19, 2001
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