👤
Home Man
Search
Today's Posts
Register

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:
Select Section of Man Page:
Select Man Page Repository:

NetBSD 6.1.5 - man page for strtol (netbsd section 3)

STRTOL(3)			   BSD Library Functions Manual 			STRTOL(3)

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

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #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>

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

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

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

DESCRIPTION
     The strtol() function converts the string in nptr to a long int value.  The strtoll() func-
     tion converts the string in nptr to a long long int value.  The strtoimax() function con-
     verts the string in nptr to an intmax_t value.  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 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 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-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.)

RETURN VALUES
     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.

EXAMPLES
     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 afterwards:

	   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 inte-
     gers 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;

ERRORS
     [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.

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

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

BUGS
     Ignores the current locale.

BSD					  July 23, 2009 				      BSD


All times are GMT -4. The time now is 04:16 PM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
×
UNIX.COM Login
Username:
Password:  
Show Password