strtoi(3) - NetBSD Manual Pages

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STRTOI(3)               NetBSD 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 deter-
     mined 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 a intmax_t value in the obvi-
     ous 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' rep-
     resenting 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 spec-
     ified 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.

NetBSD 9.3                     November 13, 2015                    NetBSD 9.3