strtol man page on OpenBSD

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STRTOL(3)		  OpenBSD Programmer's Manual		     STRTOL(3)

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

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

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

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

     #include <inttypes.h>

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

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

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

     The strtol() function converts the string in nptr to a long value.	 The
     strtoll() function converts the string in nptr to a long long value.  The
     strtoimax() function converts the string in nptr to an intmax_t value.
     The strtoq() function is a deprecated equivalent of strtoll() and is
     provided for backwards compatibility with legacy programs.	 The
     conversion is done according to the given base, which must be a number
     between 2 and 36 inclusive or the special value 0.

     The string may begin with an arbitrary amount of whitespace (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' 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, long long, or
     intmax_t, 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' representing 35.)

     If endptr is non-null, 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 strtol(), strtoll(), strtoimax(), and strtoq() functions return the
     result of the conversion, unless the value would underflow or overflow.
     If no conversion could be performed, 0 is returned; the global variable
     errno is also set to EINVAL, though this is not portable across all
     platforms.	 If overflow or underflow occurs, errno is set to ERANGE and
     the function return value is as follows:

	   Function	underflow   overflow
	   strtol()	LONG_MIN    LONG_MAX
	   strtoll()	LLONG_MIN   LLONG_MAX
	   strtoimax()	INTMAX_MIN  INTMAX_MAX
	   strtoq()	LLONG_MIN   LLONG_MAX

     Ensuring that a string is a valid number (i.e., in range and containing
     no trailing characters) requires clearing errno beforehand explicitly
     since errno is not changed on a successful call to strtol(), and the
     return value of strtol() cannot be used unambiguously to signal an error:

	   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
     trailing whitespace is acceptable, further checks must be done on *ep;
     alternately, 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;

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

     atof(3), atoi(3), atol(3), atoll(3), sscanf(3), strtod(3), strtonum(3),

     The strtol(), strtoll(), and strtoimax() functions conform to
     ANSI/ISO/IEC 9899-1999 (``ANSI C99'').  The strtoq() function is a BSD
     extension and is provided for backwards compatibility with legacy

     Ignores the current locale.

OpenBSD 4.9		       November 13, 2007		   OpenBSD 4.9

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