STRTOL(3)               NetBSD Library Functions Manual              STRTOL(3)

     strtoi, strtol, strtoll, strtoimax, strtoq -- convert string value to a
     long, long long, intmax_t or quad_t integer

     Standard C Library (libc, -lc)

     #include <stdlib.h>
     #include <limits.h>

     long int
     strtol(const char * restrict nptr, char ** restrict endptr, int base);

     long long int
     strtoll(const char * restrict nptr, char ** restrict endptr, int base);

     #include <inttypes.h>

     strtoi(const char * restrict nptr, char ** restrict endptr, int base,
         intmax_t lo, intmax_t hi, int *rstatus);

     strtoimax(const char * restrict nptr, char ** restrict endptr, int base);

     #include <sys/types.h>
     #include <stdlib.h>
     #include <limits.h>

     strtoq(const char * restrict nptr, char ** restrict endptr, int base);

     The strtol() function converts the string in nptr to a long int value.
     The strtoll() function converts the string in nptr to a long long int
     value.  The strtoimax() function converts the string in nptr to an
     intmax_t value.  The strtoi() function uses internally strtoimax() and
     ensures that the result is always in the range [ lo .. hi ].  In adddi-
     tion it always places 0 on success or a conversion status in the rstatus
     argument, avoiding the errno gymnastics the other functions require.  The
     strtoi() function doesn't affect errno on exit.  The rstatus argument can
     be NULL if conversion status is to be ignored.  The strtoq() function
     converts the string in nptr to a quad_t value.  The conversion is done
     according to the given base, which must be between 2 and 36 inclusive, or
     be the special value 0.

     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' 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 long 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' represent-
     ing 35.)

     If endptr is non-nil, strtol() stores the address of the first invalid
     character in *endptr.  If there were no digits at all, however, strtol()
     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.)

     The strtoi() function always returns the closest value in the range spec-
     ified by the lo and hi arguments.  The strtol() function returns the
     result of the conversion, unless the value would underflow or overflow.
     If an underflow occurs, strtol() returns LONG_MIN, strtoll() returns
     LLONG_MIN, and strtoimax() returns INTMAX_MIN.  If an overflow occurs,
     strtol() returns LONG_MAX, strtoll() returns LLONG_MAX, and strtoimax()
     returns INTMAX_MAX.  In these cases, errno is set to ERANGE.  If the base
     argument is not supported then errno is set to EINVAL and the functions
     return 0.

     If no error occurs, errno is left unchanged.  This behavior (which is
     unlike most library functions) is guaranteed by the pertinent standards.

     The strtoi() function is the simplest to use:

           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);

     This will always return a number in [1..99] range no matter what the
     input is, and warn if the conversion failed.

     Because the return value of strtol() cannot be used unambiguously to
     detect an error, errno is left unchanged after a successful call.  To
     ensure that a string is a valid number (i.e., in range and containing no
     trailing characters), clear errno beforehand explicitly, then check it

           char *ep;
           long lval;


           errno = 0;
           lval = strtol(buf, &ep, 10);
           if (buf[0] == '\0' || *ep != '\0')
                   goto not_a_number;
           if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
                   goto out_of_range;

     This example will accept ``12'' but not ``12foo'' or ``12\n''.  If trail-
     ing whitespace is acceptable, further checks must be done on *ep; alter-
     nately, use sscanf(3).

     If strtol() is being used instead of atoi(3), error checking is further
     complicated because the desired return value is an int rather than a
     long; however, on some architectures integers and long integers are the
     same size.  Thus the following is necessary:

           char *ep;
           int ival;
           long lval;


           errno = 0;
           lval = strtol(buf, &ep, 10);
           if (buf[0] == '\0' || *ep != '\0')
                   goto not_a_number;
           if ((errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN)) ||
               (lval > INT_MAX || lval < INT_MIN))
                   goto out_of_range;
           ival = lval;

     [EINVAL]           The base is not between 2 and 36 and does not contain
                        the special value 0.

     [ERANGE]           The given string was out of range; the value converted
                        has been clamped.

     In addition to the above errors strtoi() returns:

     [ECANCELED]        The string did not contain any characters that were

     [ENOTSUP]          The string contained non-numeric characters that did
                        not get converted.  In this case, endptr points to the
                        first unconverted character.

     [ERANGE]           The range given was invalid, i.e.  lo > hi.

     atof(3), atoi(3), atol(3), atoll(3), strtod(3), strtou(3), strtoul(3),
     strtoull(3), strtoumax(3)

     The strtol() function conforms to ANSI X3.159-1989 (``ANSI C89'').  The
     strtoll() and strtoimax() functions conform to ISO/IEC 9899:1999
     (``ISO C99'').  The strtoi() function appeared in NetBSD 8.

     Ignores the current locale.

NetBSD 7.0                      March 10, 2015                      NetBSD 7.0

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