strtoi — convert
string value to an intmax_t integer
function converts the string in nptr to an
intmax_t value. The
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
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
-’ 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
The remainder of the string is converted to a
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 ‘
If endptr is non-nil,
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
**endptr is ‘
on return, the entire string was valid.)
strtoi() function always returns the
closest value in the range specified by the lo and
The errno value is guaranteed to be left unchanged.
Errors are stored as the conversion status in the rstatus argument.
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);
- The string did not contain any characters that were converted.
- The base is not between 2 and 36 and does not contain the special value 0.
- The string contained non-numeric characters that did not get converted. In this case, endptr points to the first unconverted character.
- The given string was out of range; the value converted has been clamped; or the range given was invalid, i.e. lo > hi.
strtoi() function is a
strtoi() function first appeared in
NetBSD 7.0. OpenBSD
function for the same purpose, but the interface makes it impossible to
properly differentiate illegal returns.
Ignores the current locale.
|November 13, 2015||Debian|