[Bug c++/67799] New: The function strtoul and strtoull in <cstdlib> do not work correctly

[Bug c++/67799] New: The function strtoul and strtoull in <cstdlib> do not work correctly

[8826055 at 163 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67799

            Bug ID: 67799
           Summary: The function strtoul and strtoull in <cstdlib> do not
                    work correctly
           Product: gcc
           Version: 5.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: 8826055 at 163 dot com
  Target Milestone: ---

Created attachment 36433
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36433&action=edit
Preprocessed File

In general, they convert a char sequence representing a negative value to its
complement, while it should be the maximum positive value which can be
represented by unsigned long (or unsigned long long) by www.cplusplus.com

Here is the code:
#include <iostream>
#include <climits>
#include <cstdlib>
using namespace std;
int main() {
        cout << strtoul("-2", nullptr, 10) << endl;
        cout << ULONG_MAX << endl;
        cout << strtoull("-2", nullptr, 10) << endl;
        cout << ULLONG_MAX << endl;
        return 0;
}
and the output is:
4294967294
4294967295
18446744073709551614
18446744073709551615

I use the IDE CodeBlocks to help compile the source file. The following is the
build log.

Using built-in specs.
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D:/mingw-w64/x86_64-5.2.0-posix-seh-rt_v4-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/include

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D:/mingw-w64/x86_64-5.2.0-posix-seh-rt_v4-rev0/mingw64/bin/../libexec/gcc/x86_64-w64-mingw32/5.2.0/cc1plus.exe
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Process terminated with status 0 (0 minute(s), 0 second(s))
0 error(s), 0 warning(s) (0 minute(s), 0 second(s))

[Bug c++/67799] The function strtoul and strtoull in <cstdlib> do not work correctly

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67799

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
If you look in <cstdlib> you will see these functions are not provided by GCC's
header, they come from your C library, so this is nothing to do with GCC.

In any case, cplusplus.com is wrong, the functions behave as required by the C
standard:

  If the subject sequence begins with a minus sign, the value resulting from
  the conversion is negated (in the return type).

[Bug c++/67799] The function strtoul and strtoull in <cstdlib> do not work correctly

[8826055 at 163 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67799

8826055 at 163 dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |---

--- Comment #2 from 8826055 at 163 dot com ---
(In reply to Jonathan Wakely from comment #1)
> If you look in <cstdlib> you will see these functions are not provided by
> GCC's header, they come from your C library, so this is nothing to do with
> GCC.
> 
> In any case, cplusplus.com is wrong, the functions behave as required by the
> C standard:
> 
>   If the subject sequence begins with a minus sign, the value resulting from
>   the conversion is negated (in the return type).

But the C standard also says "If the correct value is outside the range of
representable values, LONG_MIN, LONG_MAX, LLONG_MIN, LLONG_MAX, ULONG_MAX, or
ULLONG_MAX is returned (according to the return type and sign of the value, if
any)".

[Bug c++/67799] The function strtoul and strtoull in <cstdlib> do not work correctly

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67799

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #1)
> If you look in <cstdlib> you will see these functions are not provided by
> GCC's header, they come from your C library, so this is nothing to do with
> GCC.

Again, those functions have nothing to do with GCC.

[Bug c++/67799] The function strtoul and strtoull in <cstdlib> do not work correctly

[8826055 at 163 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67799

--- Comment #4 from 8826055 at 163 dot com ---
(In reply to Jonathan Wakely from comment #3)
> (In reply to Jonathan Wakely from comment #1)
> > If you look in <cstdlib> you will see these functions are not provided by
> > GCC's header, they come from your C library, so this is nothing to do with
> > GCC.
> 
> Again, those functions have nothing to do with GCC.

Thanks, I see it. I just want to confirm that such implementation conflicts
with the C standard.

[Bug c++/67799] The function strtoul and strtoull in <cstdlib> do not work correctly

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67799

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |msebor at gcc dot gnu.org

--- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> ---
(In reply to 8826055 from comment #4)

For POSIX, see http://austingroupbugs.net/view.php?id=700

For GLIBC see
http://www.gnu.org/software/libc/manual/html_node/Parsing-of-Integers.html