|FMT_SCALED(3)||Library Functions Manual||FMT_SCALED(3)|
scan_scaled — handle numbers
with a human-readable scale
long number, char
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, Petabyte, Exabyte (computed using powers of two, i.e., Megabyte =
1024*1024). The number can have a decimal point, as in 1.5K, which returns
1536 (1024+512). If no scale factor is found, B is assumed.
fmt_scaled() function formats a number
for display using the same "human-readable" format, that is, a
number with one of the above scale factors. Numbers will be printed with a
maximum of four digits (preceded by a minus sign if the value is negative);
values such as 0B, 100B, 1023B, 1K, 1.5K, 5.5M, and so on, will be
generated. The “result” buffer must be allocated with at least
FMT_SCALED_STRSIZE bytes. The result will be
left-justified in the given space, and NUL-terminated.
fmt_scaled() functions return 0 on success. In case
of error, they return -1, leave *result as is, and set
errno to one of the following values:
ERANGE if the input string represents a number that
is too large to represent.
EINVAL if an unknown
character was used as scale factor, or if the input to
scan_scaled() was malformed, e.g., too many '.'
char *cinput = "1.5K"; long long result; if (scan_scaled(cinput, &result) == 0) printf("%s -> %lld\n", cinput, result); else fprintf(stderr, "%s - invalid\n", cinput); char buf[FMT_SCALED_STRSIZE]; long long ninput = 10483892; if (fmt_scaled(ninput, buf) == 0) printf("%lld -> %s\n", ninput, buf); else fprintf(stderr, "fmt scaled failed (errno %d)", errno);
scan_scaled() first appeared in
Ken Stailey wrote the first version of the
code that became
fmt_scaled(), originally inside
Ian Darwin excerpted this and made it into a library
routine (with significant help from Paul Janzen),
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 disk partition 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.
|July 16, 2016||OpenBSD-current|