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PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       strtol, strtoll — convert a string to a long integer

SYNOPSIS

       #include <stdlib.h>

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

DESCRIPTION

       The functionality described on this reference page is aligned with the ISO C standard. Any
       conflict between the requirements described here and the ISO C standard is  unintentional.
       This volume of POSIX.1‐2017 defers to the ISO C standard.

       These  functions  shall  convert the initial portion of the string pointed to by nptr to a
       type long and long long representation, respectively.  First,  they  decompose  the  input
       string into three parts:

        1. An  initial,  possibly  empty,  sequence  of  white-space  characters (as specified by
           isspace())

        2. A subject sequence interpreted as an integer represented in some radix  determined  by
           the value of base

        3. A  final  string of one or more unrecognized characters, including the terminating NUL
           character of the input string.

       Then they shall attempt to convert the subject sequence to  an  integer,  and  return  the
       result.

       If  the value of base is 0, the expected form of the subject sequence is that of a decimal
       constant, octal constant, or hexadecimal constant, any of which may be preceded by  a  '+'
       or  '-'  sign. A decimal constant begins with a non-zero digit, and consists of a sequence
       of decimal digits. An octal constant consists of the prefix '0' optionally followed  by  a
       sequence  of  the digits '0' to '7' only. A hexadecimal constant consists of the prefix 0x
       or 0X followed by a sequence of the decimal digits and letters 'a' (or  'A')  to  'f'  (or
       'F') with values 10 to 15 respectively.

       If  the  value of base is between 2 and 36, the expected form of the subject sequence is a
       sequence of letters and digits representing an integer with the radix specified  by  base,
       optionally  preceded  by  a '+' or '-' sign. The letters from 'a' (or 'A') to 'z' (or 'Z')
       inclusive are ascribed the values 10 to 35; only letters whose ascribed  values  are  less
       than  that  of base are permitted. If the value of base is 16, the characters 0x or 0X may
       optionally precede the sequence of letters and digits, following the sign if present.

       The subject sequence is defined as the longest initial subsequence of  the  input  string,
       starting  with  the  first  non-white-space  character  that  is of the expected form. The
       subject sequence shall contain no characters if the input  string  is  empty  or  consists
       entirely  of  white-space  characters,  or if the first non-white-space character is other
       than a sign or a permissible letter or digit.

       If the subject sequence has the expected form and the value of base is 0, the sequence  of
       characters  starting  with the first digit shall be interpreted as an integer constant. If
       the subject sequence has the expected form and the value of base is between 2 and  36,  it
       shall  be  used  as  the  base for conversion, ascribing to each letter its value as given
       above. If the subject sequence begins with a <hyphen-minus>, the value resulting from  the
       conversion  shall  be negated. A pointer to the final string shall be stored in the object
       pointed to by endptr, provided that endptr is not a null pointer.

       In other than the C or POSIX locale, additional locale-specific subject sequence forms may
       be accepted.

       If  the  subject  sequence  is  empty or does not have the expected form, no conversion is
       performed; the value of nptr shall be stored in the object pointed to by endptr,  provided
       that endptr is not a null pointer.

       These functions shall not change the setting of errno if successful.

       Since  0,  {LONG_MIN}  or {LLONG_MIN}, and {LONG_MAX} or {LLONG_MAX} are returned on error
       and are also valid  returns  on  success,  an  application  wishing  to  check  for  error
       situations should set errno to 0, then call strtol() or strtoll(), then check errno.

RETURN VALUE

       Upon  successful  completion, these functions shall return the converted value, if any. If
       no conversion could be performed, 0 shall be returned and errno may be set to [EINVAL].

       If the value of base is not supported, 0 shall be returned  and  errno  shall  be  set  to
       [EINVAL].

       If the correct value is outside the range of representable values, {LONG_MIN}, {LONG_MAX},
       {LLONG_MIN}, or {LLONG_MAX} shall be returned (according to the sign of  the  value),  and
       errno set to [ERANGE].

ERRORS

       These functions shall fail if:

       EINVAL The value of base is not supported.

       ERANGE The value to be returned is not representable.

       These functions may fail if:

       EINVAL No conversion could be performed.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Since  the  value  of  *endptr  is  unspecified  if  the  value  of base is not supported,
       applications should either ensure that base has a supported value (0 or between 2 and  36)
       before the call, or check for an [EINVAL] error before examining *endptr.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fscanf(), isalpha(), strtod()

       The Base Definitions volume of POSIX.1‐2017, <stdlib.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
       the Institute of Electrical and Electronics Engineers, Inc and The  Open  Group.   In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .