| STRTOU(3) | Library Functions Manual | STRTOU(3) | 
strtou —
#include <inttypes.h>
uintmax_t
  
  strtou(const char * restrict
    nptr, char ** restrict endptr,
    int base, uintmax_t lo,
    uintmax_t hi, int *rstatus);
strtou() function converts the string in
  nptr to an uintmax_t value. The
  strtou() function uses internally
  strtoumax(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’ 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
    uintmax_t value in the obvious manner, stopping at the end
    of the string or at the first character that does not produce 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,
    strtou() stores the address of the first invalid
    character in *endptr. If there were no digits at all,
    however, strtou() 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.)
strtou() 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.
[1..99] range no matter what the input is, and warn if
  the conversion failed.
int e; uintmax_t lval = strtou(buf, NULL, 0, 1, 99, &e); if (e) warnc(e, "conversion of `%s' to a number failed, using %ju", buf, lval);
ECANCELED]EINVAL]ENOTSUP]ERANGE]strtou() function is a
  NetBSD extension.
strtou() 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.
| November 13, 2015 | NetBSD 9.4 |