oracular (3) strtoi.3bsd.gz

NAME

     strtoi — convert a string value to an intmax_t integer

LIBRARY

     Utility functions from BSD systems (libbsd, -lbsd)

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.