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

NAME

       strtol, strtoll, strtoq - convert a string to a long integer

SYNOPSIS

       #include <stdlib.h>

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

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

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       strtoll():
	   _ISOC99_SOURCE
	       || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE

DESCRIPTION

       The  strtol()  function	converts the initial part of the string in nptr to a long integer value 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" 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 long int 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 uppercase or lowercase represents 10, 'B' represents 11, and so
       forth, with 'Z' representing 35.)

       If endptr is not NULL, strtol() stores the address of the first invalid character in *endptr.  If there were no	digits	at  all,  strtol()
       stores  the  original  value  of  nptr in *endptr (and returns 0).  In particular, if *nptr is not '' but **endptr is '' on return, the
       entire string is valid.

       The strtoll() function works just like the strtol() function but returns a long long integer value.

RETURN VALUE

       The strtol() function returns the result of the conversion, unless the value would underflow or overflow.  If an underflow occurs, strtol()
       returns	LONG_MIN.  If an overflow occurs, strtol() returns LONG_MAX.  In both cases, errno is set to ERANGE.  Precisely the same holds for
       strtoll() (with LLONG_MIN and LLONG_MAX instead of LONG_MIN and LONG_MAX).

ERRORS

       EINVAL (not in C99) The given base contains an unsupported value.

       ERANGE The resulting value was out of range.

       The implementation may also set errno to EINVAL in case no conversion was performed (no digits seen, and 0 returned).

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +------------------------------+---------------+----------------+
       |Interface		      | Attribute     | Value	       |
       +------------------------------+---------------+----------------+
       |strtol(), strtoll(), strtoq() | Thread safety | MT-Safe locale |
       +------------------------------+---------------+----------------+
CONFORMING TO

       strtol(): POSIX.1-2001, POSIX.1-2008, C89, C99 SVr4, 4.3BSD.

       strtoll(): POSIX.1-2001, POSIX.1-2008, C99.

NOTES

       Since strtol() can legitimately return 0, LONG_MAX, or LONG_MIN (LLONG_MAX or LLONG_MIN for strtoll()) on both  success	and  failure,  the
       calling	program  should  set  errno  to 0 before the call, and then determine if an error occurred by checking whether errno has a nonzero
       value after the call.

       According to POSIX.1, in locales other than the "C" and "POSIX", these functions may accept other, implementation-defined numeric strings.

       BSD also has

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

       with completely analogous definition.  Depending on the wordsize of the current architecture, this may be equivalent  to  strtoll()  or	to
       strtol().

EXAMPLE

       The  program  shown  below demonstrates the use of strtol().  The first command-line argument specifies a string from which strtol() should
       parse a number.	The second (optional) argument specifies the base to be used for the conversion.  (This argument is converted  to  numeric
       form  using  atoi(3),  a function that performs no error checking and has a simpler interface than strtol().)  Some examples of the results
       produced by this program are the following:

	   $ ./a.out 123
	   strtol() returned 123
	   $ ./a.out '	  123'
	   strtol() returned 123
	   $ ./a.out 123abc
	   strtol() returned 123
	   Further characters after number: abc
	   $ ./a.out 123abc 55
	   strtol: Invalid argument
	   $ ./a.out ''
	   No digits were found
	   $ ./a.out 4000000000
	   strtol: Numerical result out of range

   Program source

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

       int
       main(int argc, char *argv[])
       {
	   int base;
	   char *endptr, *str;
	   long val;

	   if (argc < 2) {
	       fprintf(stderr, "Usage: %s str [base]
", argv[0]);
	       exit(EXIT_FAILURE);
	   }

	   str = argv[1];
	   base = (argc > 2) ? atoi(argv[2]) : 10;

	   errno = 0;	 /* To distinguish success/failure after call */
	   val = strtol(str, &endptr, base);

	   /* Check for various possible errors */

	   if ((errno == ERANGE && (val == LONG_MAX || val == LONG_MIN))
		   || (errno != 0 && val == 0)) {
	       perror("strtol");
	       exit(EXIT_FAILURE);
	   }

	   if (endptr == str) {
	       fprintf(stderr, "No digits were found
");
	       exit(EXIT_FAILURE);
	   }

	   /* If we got here, strtol() successfully parsed a number */

	   printf("strtol() returned %ld
", val);

	   if (*endptr != '')        /* Not necessarily an error... */
	       printf("Further characters after number: %s
", endptr);

	   exit(EXIT_SUCCESS);
       }

SEE ALSO

       atof(3), atoi(3), atol(3), strtod(3), strtoul(3)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU
								    2017-09-15								 STRTOL(3)