strtoi(3bsd) | 3bsd | strtoi(3bsd) |
NAME
strtoi
— convert a
string value to an intmax_t integer
LIBRARY
library “libbsd”
SYNOPSIS
#include
<inttypes.h>
(See
libbsd(7) for include usage.)
intmax_t
strtoi
(const char * restrict
nptr, char ** restrict endptr,
int base, intmax_t lo,
intmax_t hi, int *rstatus);
DESCRIPTION
The
strtoi
()
function converts the string in nptr to an
intmax_t value. The strtoi
()
function uses internally
strtoimax(3) and ensures that
the result is always in the range [ lo ..
hi ]. In addition it always places
0
on success or a conversion status in the
rstatus argument, avoiding the
errno
gymnastics the other functions require. The
rstatus argument can be NULL
if conversion status is to be ignored.
The string may begin with an arbitrary amount of white space (as
determined by isspace(3))
followed by a single optional ‘+
’ or
‘-
’ sign. If
base is zero or 16, the string may then include a
‘0x
’ or
‘0X
’ prefix, and the number will be
read in base 16; otherwise, a zero base is taken as 10
(decimal) unless the next character is
‘0
’, in which case it is taken as 8
(octal).
The remainder of the string is converted to an
intmax_t value
in the obvious manner, stopping at the end of the string or at the first
character which is not a valid digit in the given base. (In bases above 10,
the letter ‘A
’ in either upper or
lower case represents 10, ‘B
’
represents 11, and so forth, with ‘Z
’
representing 35.)
If endptr is non-nil,
strtoi
()
stores the address of the first invalid character in
*endptr. If there were no digits at all, however,
strtoi
() stores the original value of
nptr in *endptr. (Thus, if
*nptr is not
‘\0
’ but
**endptr is ‘\0
’
on return, the entire string was valid.)
RETURN VALUES
The strtoi
() function always returns the
closest value in the range specified by the lo and
hi arguments.
The errno value is guaranteed to be left unchanged.
Errors are stored as the conversion status in the rstatus argument.
EXAMPLES
The following example will always return a number in
[1..99]
range no matter what the input is, and warn
if the conversion failed.
int e; intmax_t lval = strtoi(buf, NULL, 0, 1, 99, &e); if (e) warnc(e, "conversion of `%s' to a number failed, using %jd", buf, lval);
ERRORS
- [
ECANCELED
] - The string did not contain any characters that were converted.
- [
EINVAL
] - The base is not between 2 and 36 and does not contain the special value 0.
- [
ENOTSUP
] - The string contained non-numeric characters that did not get converted. In this case, endptr points to the first unconverted character.
- [
ERANGE
] - The given string was out of range; the value converted has been clamped; or the range given was invalid, i.e. lo > hi.
The range check is more important than the unconverted characters check, and it is performed first. If a program needs to know if there were unconverted characters when an out of range number has been provided, it needs to supply and test endptr.
SEE ALSO
atof(3), atoi(3), atol(3), atoll(3), strtod(3), strtoimax(3), strtol(3), strtoll(3), strtou(3bsd), strtoul(3), strtoull(3), strtoumax(3)
STANDARDS
The strtoi
() function is a
NetBSD extension.
HISTORY
The strtoi
() function first appeared in
NetBSD 7.0. OpenBSD
introduced the strtonum(3bsd)
function for the same purpose, but the interface makes it impossible to
properly differentiate illegal returns.
BUGS
Ignores the current locale.
January 20, 2024 | Linux 6.10.2-arch1-1 |