min and max value of data type in C

Question

What is the function to determine the min and max possible of value of datatypes  i e  int  char etc  in C

User · Answer

Look at the these pages on limits h and float h  which are included as part of the standard c library

User · Answer

Maximum value of any unsigned integral type      t   t 0     Generic expression that would work in almost all circumstances     t 0     If you know your type t have equal or larger size than unsigned int   This cast forces type promotion     t  0U     If you know your type t have smaller size than unsigned int   This cast demotes type after the unsigned int-type expression  0U is evaluated     Maximum value of any signed integral type    If you have an unsigned variant of type t    t    unsigned t   unsigned t 0  gt  gt 1   would give you the fastest result you need  Otherwise  use this  thanks to  vinc17 for suggestion      1ULL lt  lt  sizeof t  CHAR BIT-2  -1  2 1    Minimum value of any signed integral type   You have to know the signed number representation of your machine  Most machines use 2 s complement  and so -   1ULL lt  lt  sizeof t  CHAR BIT-2  -1  2 1 -1 will work for you   To detect whether your machine uses 2 s complement  detect whether    t 0U  and  t  -1  represent the same thing   So  combined with above    -   1ULL lt  lt  sizeof t  CHAR BIT-2  -1  2 1 -     t 0U    t  -1      will give you the minimum value of any signed integral type   As an example  Maximum value of size t  a k a  the SIZE MAX macro  can be defined as    size t 0   Linux kernel source code define SIZE MAX macro this way   One caveat though  All of these expressions use either type casting or sizeof operator and so none of these would work in preprocessor conditionals   if      elif      endif and like     Answer updated for incorpoating suggestions from  chux and  vinc17  Thank you both

User · Answer

MIN and MAX values of any integer data type can be computed without using any library functions as below and same logic can be applied to other integer types short  int and long   printf  Signed Char   MIN - gt   d  amp  Max - gt   d n     char   unsigned char  0 gt  gt 1    char   unsigned char  0  gt  gt  1    printf  Unsigned Char   MIN - gt   u  amp  Max - gt   u n    unsigned char 0   unsigned char   0

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You ll want to use limits h which provides the following constants  as per the linked reference   SCHAR MIN        minimum value for a signed char SCHAR MAX        maximum value for a signed char UCHAR MAX        maximum value for an unsigned char CHAR MIN         minimum value for a char CHAR MAX         maximum value for a char SHRT MIN         minimum value for a short SHRT MAX         maximum value for a short USHRT MAX        maximum value for an unsigned short INT MIN          minimum value for an int INT MAX          maximum value for an int UINT MAX         maximum value for an unsigned int LONG MIN         minimum value for a long LONG MAX         maximum value for a long ULONG MAX        maximum value for an unsigned long LLONG MIN        minimum value for a long long LLONG MAX        maximum value for a long long ULLONG MAX       maximum value for an unsigned long long PTRDIFF MIN      minimum value of ptrdiff t PTRDIFF MAX      maximum value of ptrdiff t SIZE MAX         maximum value of size t SIG ATOMIC MIN   minimum value of sig atomic t SIG ATOMIC MAX   maximum value of sig atomic t WINT MIN         minimum value of wint t WINT MAX         maximum value of wint t WCHAR MIN        minimum value of wchar t WCHAR MAX        maximum value of wchar t CHAR BIT         number of bits in a char MB LEN MAX       maximum length of a multibyte character in bytes  Where U  MIN is omitted for obvious reasons  any unsigned type has a minimum value of 0   Similarly float h provides limits for float and double types  FLT MIN      smallest normalised positive value of a float FLT MAX      largest positive finite value of a float DBL MIN      smallest normalised positive value of a double DBL MAX      largest positive finite value of a double LDBL MIN     smallest normalised positive value of a long double LDBL MAX     largest positive finite value of a long double FLT DIG      the number of decimal digits guaranteed to be preserved converting from text to float and back to text DBL DIG      the number of decimal digits guaranteed to be preserved converting from text to double and back to text LDBL DIG     the number of decimal digits guaranteed to be preserved converting from text to long double and back to text  Floating point types are symmetrical around zero  so the most negative finite number is the negation of the most positive finite number - eg float ranges from -FLT MAX to FLT MAX  Do note that floating point types can only exactly represent a small  finite number of values within their range   As the absolute values stored get larger  the spacing between adjacent numbers that can be exactly represented also gets larger

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I wrote some macros that return the min and max of any type  regardless of signedness    define MAX OF type           type   0LLU   gt   type   1LLU lt  lt   sizeof type  lt  lt 3 -1  -1LLU      long long unsigned int  type   0LLU     long long unsigned int  type   1LLU lt  lt   sizeof type  lt  lt 3 -1  -1LLU    define MIN OF type           type  1LLU lt  lt   sizeof type  lt  lt 3 -1    lt   type 1     long long int    0LLU -  1LLU lt  lt   sizeof type  lt  lt 3 -1  -1LLU     0LL    Example code    include  lt stdio h gt   include  lt sys types h gt   include  lt inttypes h gt    define MAX OF type           type   0LLU   gt   type   1LLU lt  lt   sizeof type  lt  lt 3 -1  -1LLU      long long unsigned int  type   0LLU     long long unsigned int  type   1LLU lt  lt   sizeof type  lt  lt 3 -1  -1LLU    define MIN OF type           type  1LLU lt  lt   sizeof type  lt  lt 3 -1    lt   type 1     long long int    0LLU -  1LLU lt  lt   sizeof type  lt  lt 3 -1  -1LLU     0LL   int main void        printf  uint32 t    lld   llu n   MIN OF uint32 t   MAX OF uint32 t        printf  int32 t    lld   llu n   MIN OF int32 t   MAX OF int32 t        printf  uint64 t    lld   llu n   MIN OF uint64 t   MAX OF uint64 t        printf  int64 t    lld   llu n   MIN OF int64 t   MAX OF int64 t        printf  size t    lld   llu n   MIN OF size t   MAX OF size t        printf  ssize t    lld   llu n   MIN OF ssize t   MAX OF ssize t        printf  pid t    lld   llu n   MIN OF pid t   MAX OF pid t        printf  time t    lld   llu n   MIN OF time t   MAX OF time t        printf  intptr t    lld   llu n   MIN OF intptr t   MAX OF intptr t        printf  unsigned char    lld   llu n   MIN OF unsigned char   MAX OF unsigned char        printf  char    lld   llu n   MIN OF char   MAX OF char        printf  uint8 t    lld   llu n   MIN OF uint8 t   MAX OF uint8 t        printf  int8 t    lld   llu n   MIN OF int8 t   MAX OF int8 t        printf  uint16 t    lld   llu n   MIN OF uint16 t   MAX OF uint16 t        printf  int16 t    lld   llu n   MIN OF int16 t   MAX OF int16 t        printf  int    lld   llu n   MIN OF int   MAX OF int        printf  long int    lld   llu n   MIN OF long int   MAX OF long int        printf  long long int    lld   llu n   MIN OF long long int   MAX OF long long int        printf  off t    lld   llu n   MIN OF off t   MAX OF off t         return 0

User · Answer

The header file limits h defines macros that expand to various limits and parameters of the standard integer types

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But glyph   I hear you asking   what if I have to determine the maximum value for an opaque type whose maximum might eventually change    You might continue   What if it s a typedef in a library I don t control    I m glad you asked  because I just spent a couple of hours cooking up a solution  which I then had to throw away  because it didn t solve my actual problem    You can use this handy maxof macro to determine the size of any valid integer type    define issigned t     t  -1    lt    t  0     define umaxof t     0x1ULL  lt  lt    sizeof t    8ULL  - 1ULL   - 1ULL                           0xFULL  lt  lt    sizeof t    8ULL  - 4ULL      define smaxof t     0x1ULL  lt  lt    sizeof t    8ULL  - 1ULL   - 1ULL                           0x7ULL  lt  lt    sizeof t    8ULL  - 4ULL      define maxof t    unsigned long long   issigned t    smaxof t    umaxof t      You can use it like so   int main int argc  char   argv        printf  schar   llx uchar   llx n   maxof char   maxof unsigned char        printf  sshort   llx ushort   llx n   maxof short   maxof unsigned short        printf  sint   llx uint   llx n   maxof int   maxof unsigned int        printf  slong   llx ulong   llx n   maxof long   maxof unsigned long        printf  slong long   llx ulong long   llx n              maxof long long   maxof unsigned long long        return 0      If you d like  you can toss a   t   onto the front of those macros so they give you a result of the type that you re asking about  and you don t have to do casting to avoid warnings

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include lt stdio h gt   int main void        printf  Minimum Signed Char  d n  - char   unsigned char   0  gt  gt  1  - 1       printf  Maximum Signed Char  d n   char    unsigned char   0  gt  gt  1         printf  Minimum Signed Short  d n  - short   unsigned short  0  gt  gt 1  -1       printf  Maximum Signed Short  d n   short   unsigned short  0  gt  gt  1         printf  Minimum Signed Int  d n  - int   unsigned int  0  gt  gt  1  -1       printf  Maximum Signed Int  d n   int   unsigned int  0  gt  gt  1         printf  Minimum Signed Long  ld n  - long   unsigned long  0  gt  gt 1  -1       printf  Maximum signed Long  ld n   long   unsigned long  0  gt  gt  1            Unsigned Maximum Values         printf  Maximum Unsigned Char  d n   unsigned char  0       printf  Maximum Unsigned Short  d n   unsigned short  0       printf  Maximum Unsigned Int  u n   unsigned int  0       printf  Maximum Unsigned Long  lu n   unsigned long  0        return 0

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To get the maximum value of an unsigned integer type t whose width is at least the one of unsigned int  otherwise one gets problems with integer promotions     t  0  If one wants to also support shorter types  one can add another cast   t    t  0   If the integer type t is signed  assuming that there are no padding bits  one can use       t  1  lt  lt   sizeof t    CHAR BIT - 2   - 1    2   1    The advantage of this formula is that it is not based on some unsigned version of t  or a larger type   which may be unknown or unavailable  even uintmax t may not be sufficient with non-standard extensions   Example with 6 bits  not possible in practice  just for readability    010000   t  1  lt  lt   sizeof t    CHAR BIT - 2  001111  - 1 011110    2 011111    1   In two s complement  the minimum value is the opposite of the maximum value  minus 1  in the other integer representations allowed by the ISO C standard  this is just the opposite of the maximum value    Note  To detect signedness in order to decide which version to use   t  -1  lt  0 will work with any integer representation  giving 1  true  for signed integer types and 0  false  for unsigned integer types  Thus one can use    t  -1  lt  0       t  1  lt  lt   sizeof t    CHAR BIT - 2   - 1    2   1     t    t  0

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