[Langage C] Overflow, limite ?

/* Copyright (C) 1991, 1992, 1996, 1997, 1998, 1999, 2000, 2005
   Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

/*
 *	ISO C99 Standard: 7.10/5.2.4.2.1 Sizes of integer types	<limits.h>
 */

#ifndef _LIBC_LIMITS_H_
#define _LIBC_LIMITS_H_	1

#include <features.h>


/* Maximum length of any multibyte character in any locale.
   We define this value here since the gcc header does not define
   the correct value.  */
#define MB_LEN_MAX	16


/* If we are not using GNU CC we have to define all the symbols ourself.
   Otherwise use gcc's definitions (see below).  */
#if !defined __GNUC__ || __GNUC__ < 2

/* We only protect from multiple inclusion here, because all the other
   #include's protect themselves, and in GCC 2 we may #include_next through
   multiple copies of this file before we get to GCC's.  */
# ifndef _LIMITS_H
#  define _LIMITS_H	1

#include <bits/wordsize.h>

/* We don't have #include_next.
   Define ANSI <limits.h> for standard 32-bit words.  */

/* These assume 8-bit `char's, 16-bit `short int's,
   and 32-bit `int's and `long int's.  */

/* Number of bits in a `char'.	*/
#  define CHAR_BIT	8

/* Minimum and maximum values a `signed char' can hold.  */
#  define SCHAR_MIN	(-128)
#  define SCHAR_MAX	127

/* Maximum value an `unsigned char' can hold.  (Minimum is 0.)  */
#  define UCHAR_MAX	255

/* Minimum and maximum values a `char' can hold.  */
#  ifdef __CHAR_UNSIGNED__
#   define CHAR_MIN	0
#   define CHAR_MAX	UCHAR_MAX
#  else
#   define CHAR_MIN	SCHAR_MIN
#   define CHAR_MAX	SCHAR_MAX
#  endif

/* Minimum and maximum values a `signed short int' can hold.  */
#  define SHRT_MIN	(-32768)
#  define SHRT_MAX	32767

/* Maximum value an `unsigned short int' can hold.  (Minimum is 0.)  */
#  define USHRT_MAX	65535

/* Minimum and maximum values a `signed int' can hold.  */
#  define INT_MIN	(-INT_MAX - 1)
#  define INT_MAX	2147483647

/* Maximum value an `unsigned int' can hold.  (Minimum is 0.)  */
#  define UINT_MAX	4294967295U

/* Minimum and maximum values a `signed long int' can hold.  */
#  if __WORDSIZE == 64
#   define LONG_MAX	9223372036854775807L
#  else
#   define LONG_MAX	2147483647L
#  endif
#  define LONG_MIN	(-LONG_MAX - 1L)

/* Maximum value an `unsigned long int' can hold.  (Minimum is 0.)  */
#  if __WORDSIZE == 64
#   define ULONG_MAX	18446744073709551615UL
#  else
#   define ULONG_MAX	4294967295UL
#  endif

#  ifdef __USE_ISOC99

/* Minimum and maximum values a `signed long long int' can hold.  */
#   define LLONG_MAX	9223372036854775807LL
#   define LLONG_MIN	(-LLONG_MAX - 1LL)

/* Maximum value an `unsigned long long int' can hold.  (Minimum is 0.)  */
#   define ULLONG_MAX	18446744073709551615ULL

#  endif /* ISO C99 */

# endif	/* limits.h  */
#endif	/* GCC 2.  */

#endif	/* !_LIBC_LIMITS_H_ */

 /* Get the compiler's limits.h, which defines almost all the ISO constants.

    We put this #include_next outside the double inclusion check because
    it should be possible to include this file more than once and still get
    the definitions from gcc's header.  */
#if defined __GNUC__ && !defined _GCC_LIMITS_H_
/* `_GCC_LIMITS_H_' is what GCC's file defines.  */
# include_next <limits.h>
#endif

/* The <limits.h> files in some gcc versions don't define LLONG_MIN,
   LLONG_MAX, and ULLONG_MAX.  Instead only the values gcc defined for
   ages are available.  */
#if defined __USE_ISOC99 && defined __GNUC__
# ifndef LLONG_MIN
#  define LLONG_MIN	(-LLONG_MAX-1)
# endif
# ifndef LLONG_MAX
#  define LLONG_MAX	__LONG_LONG_MAX__
# endif
# ifndef ULLONG_MAX
#  define ULLONG_MAX	(LLONG_MAX * 2ULL + 1)
# endif
#endif

#ifdef	__USE_POSIX
/* POSIX adds things to <limits.h>.  */
# include <bits/posix1_lim.h>
#endif

#ifdef	__USE_POSIX2
# include <bits/posix2_lim.h>
#endif

#ifdef	__USE_XOPEN
# include <bits/xopen_lim.h>
#endif

#include<stdio.h>

int main()
{
        printf("char min = %d, char max = %d\n",
                -(char)((unsigned char)~0>>1),
                (char)((unsigned char)~0>>1));
        printf("int min = %d, int max = %d\n",
                -(int)((unsigned int)~0>>1),
                (int)((unsigned int)~0>>1));
        return 0;
}

      printf("int = %d octets\n", sizeof(int)); // 4 octets
      printf("short = %d octets\n", sizeof(short)); // 2 octets
      printf("float = %d octets\n", sizeof(float)); // 4 octets
      printf("double %d octets\n\n", sizeof(double)); // 8 octets

taille_variable_octet * 8 (pour obtenir le nombre de bits) = x
2^x = taille maximum non signé 
x/2 = y
taille de la variable signé = -y à y

4*8 = 32
2^32 = 4294967296 (Valeur non signé de int : unsigned int)
4294967296/2 = 2147483648

Valeur minimum int = -2147483648
Valeur maximum int = 2147483648