STRTOI(3) |
Library Functions Manual |
STRTOI(3) |
NAME
strtoi — convert string value to an intmax_t integer
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <inttypes.h>
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 adddition 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
’ 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 a intmax_t value in the obvious manner, stopping 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.
SEE ALSO
atof(3),
atoi(3),
atol(3),
atoll(3),
strtod(3),
strtoimax(3),
strtol(3),
strtoll(3),
strtou(3),
strtoul(3),
strtoull(3),
strtoumax(3)
STANDARDS
The strtoi() function is a NetBSD extension.
HISTORY
The strtoi() function first appeared in NetBSD 7. OpenBSD introduced the strtonum(3) function for the same purpose, but the interface makes it impossible to properly differentiate illegal returns.
BUGS
Ignores the current locale.