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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: More trouble with strtoul
Date: Fri, 20 Mar 2015 10:56:57 -0700
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jacob navia <jacob@jacob.remcomp.fr> writes:
> d:\lcc\libc\test>gcc -v
> Using built-in specs.
> COLLECT_GCC=gcc
> COLLECT_LTO_WRAPPER=c:/tdm-gcc-64/bin/../libexec/gcc/x86_64-w64-mingw32/4.8.1/lto-wrapper.exe
> Target: x86_64-w64-mingw32
> Configured with: ../../../src/gcc-4.8.1/configure
> --build=x86_64-w64-mingw32 --enable-targets=all --enable-lan
> guages=ada,c,c++,fortran,lto,objc,obj-c++ --enable-libgomp
> --enable-lto --enable-graphite --enable-cxx-flags=-
> DWINPTHREAD_STATIC --enable-libstdcxx-debug --enable-threads=posix
> --enable-version-specific-runtime-libs --en
> able-fully-dynamic-string --enable-libstdcxx-threads
> --enable-libstdcxx-time --with-gnu-ld --disable-werror --
> disable-nls --disable-win32-registry --prefix=/mingw64tdm
> --with-local-prefix=/mingw64tdm --with-pkgversion=td
> m64-2 --with-bugurl=http://tdm-gcc.tdragon.net/bugs
> Thread model: posix
> gcc version 4.8.1 (tdm64-2)

Since you're using MinGW, I believe the strtol implementation is
provided by Microsoft's runtime library, not by either gcc or glibc.  It
could be a bug in Microsoft's library, in MinGW's integration of gcc
with the library (I know it has problems with long double), or in your
test program.  I have my suspicions, but there's no point in
speculating.

I suggest trying my test program (see below) with the gcc you'reusing,
with MinGW, and with Microsoft's implementation.

If you have problems with "-4294967296" with 32-bit unsigned long, it's
likely you'd have similar problems with "-18446744073709551616" with
64-bit long.  Here's an updated test program that allows for both
possibilities.  With gcc, compiling with "-m32" (if supported) gives you
32-bit long.

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <errno.h>
int main(void) {
    printf("ULONG_MAX = %lu (0x%lx)\n", ULONG_MAX, ULONG_MAX);

    errno = 0;
#if ULONG_MAX == 4294967295U
    unsigned long result = strtoul("-4294967296", NULL, 0);
#elif ULONG_MAX == 18446744073709551615U
    unsigned long result = strtoul("-18446744073709551616", NULL, 0);
#else
    #error "Unexpected value for ULONG_MAX"
#endif

    printf("result = %lu (0x%lx), errno = %d",
           result, result, errno);
    if (errno == ERANGE) {
        printf(" (ERANGE)");
    }
    putchar('\n');
}

On my system, with "-m32", I get:

    ULONG_MAX = 4294967295 (0xffffffff)
    result = 4294967295 (0xffffffff), errno = 34 (ERANGE)

Without "-m32", I get:

    ULONG_MAX = 18446744073709551615 (0xffffffffffffffff)
    result = 18446744073709551615 (0xffffffffffffffff), errno = 34 (ERANGE)

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"