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      Numeric limits

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      [edit]Limits of integer types

      Limits of core language integer types
      Defined in header <limits.h>
      BOOL_WIDTH
      (C23)
      		 bit width of _Bool
      (macro constant)
      CHAR_BIT
      		 bit width of byte
      (macro constant)[edit]
      MB_LEN_MAX
      		 maximum number of bytes in a multibyte character
      (macro constant)[edit]
      CHAR_WIDTH
      (C23)
      		 bit width of char, same as CHAR_BIT
      (macro constant)
      CHAR_MIN
      		 minimum value of char
      (macro constant)[edit]
      CHAR_MAX
      		 maximum value of char
      (macro constant)[edit]
      SCHAR_WIDTHSHRT_WIDTHINT_WIDTHLONG_WIDTHLLONG_WIDTH
      (C23)(C23)(C23)(C23)(C23)
      		 bit width of signedchar, short, int, long, and longlong respectively
      (macro constant)
      SCHAR_MINSHRT_MININT_MINLONG_MINLLONG_MIN
      (C99)
      		 minimum value of signedchar, short, int, long and longlong respectively
      (macro constant)[edit]
      SCHAR_MAXSHRT_MAXINT_MAXLONG_MAXLLONG_MAX
      (C99)
      		 maximum value of signedchar, short, int, long and longlong respectively
      (macro constant)[edit]
      UCHAR_WIDTHUSHRT_WIDTHUINT_WIDTHULONG_WIDTHULLONG_WIDTH
      (C23)(C23)(C23)(C23)(C23)
      		 bit width of unsignedchar, unsignedshort, unsignedint, unsignedlong, and unsignedlonglong respectively
      (macro constant)
      UCHAR_MAXUSHRT_MAXUINT_MAXULONG_MAXULLONG_MAX
      (C99)
      		 maximum value of unsignedchar, unsignedshort, unsignedint,
      unsignedlong and unsignedlonglong respectively
      (macro constant)[edit]
      BITINT_MAXWIDTH
      (C23)
      		 maximum width N supported by the declaration of a bit-precise integer in the type specifier _BitInt(N), greater than or equal to ULLONG_WIDTH
      (macro constant)
      Limits of library type aliases
      Defined in header <stdint.h>
      PTRDIFF_WIDTH
      (C23)
      		 bit width of object of ptrdiff_t type
      (macro constant)
      PTRDIFF_MIN
      (C99)
      		 minimum value of ptrdiff_t
      (macro constant)[edit]
      PTRDIFF_MAX
      (C99)
      		 maximum value of ptrdiff_t
      (macro constant)[edit]
      SIZE_WIDTH
      (C23)
      		 bit width of object of size_t type
      (macro constant)
      SIZE_MAX
      (C99)
      		 maximum value of size_t
      (macro constant)[edit]
      SIG_ATOMIC_WIDTH
      (C23)
      		 bit width of object of sig_atomic_t type
      (macro constant)
      SIG_ATOMIC_MIN
      (C99)
      		 minimum value of sig_atomic_t
      (macro constant)[edit]
      SIG_ATOMIC_MAX
      (C99)
      		 maximum value of sig_atomic_t
      (macro constant)[edit]
      WINT_WIDTH
      (C23)
      		 bit width of object of wint_t type
      (macro constant)
      WINT_MIN
      (C99)
      		 minimum value of wint_t
      (macro constant)[edit]
      WINT_MAX
      (C99)
      		 maximum value of wint_t
      (macro constant)[edit]
      Defined in header <wchar.h>
      Defined in header <stdint.h>
      WCHAR_WIDTH
      (C23)
      		 bit width of object of wchar_t type
      (macro constant)
      WCHAR_MIN
      (C99)
      		 minimum value of wchar_t
      (macro constant)[edit]
      WCHAR_MAX
      (C99)
      		 maximum value of wchar_t
      (macro constant)[edit]

      [edit]Notes

      The types of these constants, other than CHAR_BIT and MB_LEN_MAX, are required to match the results of the integral promotions as applied to objects of the types they describe: CHAR_MAX may have type int or unsignedint, but never char. Similarly USHRT_MAX may not be of an unsigned type: its type may be int.

      A freestanding implementation may lack sig_atomic_t and/or wint_t typedef names, in which case the SIG_ATOMIC_* and/or WINT_* macros are correspondingly absent.

      [edit]Example

      Run this code
      #include <limits.h>#include <stdint.h>#include <stdio.h>   int main(void){printf("CHAR_BIT = %d\n", CHAR_BIT);printf("MB_LEN_MAX = %d\n\n", MB_LEN_MAX);   printf("CHAR_MIN = %+d\n", CHAR_MIN);printf("CHAR_MAX = %+d\n", CHAR_MAX);printf("SCHAR_MIN = %+d\n", SCHAR_MIN);printf("SCHAR_MAX = %+d\n", SCHAR_MAX);printf("UCHAR_MAX = %u\n\n", UCHAR_MAX);   printf("SHRT_MIN = %+d\n", SHRT_MIN);printf("SHRT_MAX = %+d\n", SHRT_MAX);printf("USHRT_MAX = %u\n\n", USHRT_MAX);   printf("INT_MIN = %+d\n", INT_MIN);printf("INT_MAX = %+d\n", INT_MAX);printf("UINT_MAX = %u\n\n", UINT_MAX);   printf("LONG_MIN = %+ld\n", LONG_MIN);printf("LONG_MAX = %+ld\n", LONG_MAX);printf("ULONG_MAX = %lu\n\n", ULONG_MAX);   printf("LLONG_MIN = %+lld\n", LLONG_MIN);printf("LLONG_MAX = %+lld\n", LLONG_MAX);printf("ULLONG_MAX = %llu\n\n", ULLONG_MAX);   printf("PTRDIFF_MIN = %td\n", PTRDIFF_MIN);printf("PTRDIFF_MAX = %+td\n", PTRDIFF_MAX);printf("SIZE_MAX = %zu\n", SIZE_MAX);printf("SIG_ATOMIC_MIN = %+jd\n",(intmax_t)SIG_ATOMIC_MIN);printf("SIG_ATOMIC_MAX = %+jd\n",(intmax_t)SIG_ATOMIC_MAX);printf("WCHAR_MIN = %+jd\n",(intmax_t)WCHAR_MIN);printf("WCHAR_MAX = %+jd\n",(intmax_t)WCHAR_MAX);printf("WINT_MIN = %jd\n", (intmax_t)WINT_MIN);printf("WINT_MAX = %jd\n", (intmax_t)WINT_MAX);}

      Possible output: 

      CHAR_BIT = 8 MB_LEN_MAX = 16   CHAR_MIN = -128 CHAR_MAX = +127 SCHAR_MIN = -128 SCHAR_MAX = +127 UCHAR_MAX = 255   SHRT_MIN = -32768 SHRT_MAX = +32767 USHRT_MAX = 65535   INT_MIN = -2147483648 INT_MAX = +2147483647 UINT_MAX = 4294967295   LONG_MIN = -9223372036854775808 LONG_MAX = +9223372036854775807 ULONG_MAX = 18446744073709551615   LLONG_MIN = -9223372036854775808 LLONG_MAX = +9223372036854775807 ULLONG_MAX = 18446744073709551615   PTRDIFF_MIN = -9223372036854775808 PTRDIFF_MAX = +9223372036854775807 SIZE_MAX = 18446744073709551615 SIG_ATOMIC_MIN = -2147483648 SIG_ATOMIC_MAX = +2147483647 WCHAR_MIN = -2147483648 WCHAR_MAX = +2147483647 WINT_MIN = 0 WINT_MAX = 4294967295

      [edit]Limits of floating-point types

      Defined in header <float.h>
      FLT_RADIX
      		 the radix (integer base) used by the representation of all three floating-point types
      (macro constant)
      DECIMAL_DIG
      (C99)
      		 conversion from longdouble to decimal with at least DECIMAL_DIG digits and back to longdouble is the identity conversion: this is the decimal precision required to serialize/deserialize a longdouble
      (macro constant)
      FLT_DECIMAL_DIGDBL_DECIMAL_DIGLDBL_DECIMAL_DIG
      (C11)
      		 conversion from float/double/longdouble to decimal with at least FLT_DECIMAL_DIG/DBL_DECIMAL_DIG/LDBL_DECIMAL_DIG digits and back is the identity conversion: this is the decimal precision required to serialize/deserialize a floating-point value. Defined to at least 6, 10, and 10 respectively, or 9 for IEEE float and 17 for IEEE double (see also the C++ analog: max_digits10)
      (macro constant)
      FLT_MINDBL_MINLDBL_MIN
      		 minimum, normalized, positive value of float, double and longdouble respectively
      (macro constant)
      FLT_TRUE_MINDBL_TRUE_MINLDBL_TRUE_MIN
      (C11)
      		 minimum positive value of float, double and longdouble respectively
      (macro constant)
      FLT_MAXDBL_MAXLDBL_MAX
      		 maximum finite value of float, double and longdouble respectively
      (macro constant)
      FLT_EPSILONDBL_EPSILONLDBL_EPSILON
      		 absolute value difference between 1.0 and the next representable value for float, double and longdouble respectively
      (macro constant)
      FLT_DIGDBL_DIGLDBL_DIG
      		 number of decimal digits that are guaranteed to be preserved in text → float/double/longdouble → text roundtrip without change due to rounding or overflow (see the C++ analog digits10 for detail)
      (macro constant)
      FLT_MANT_DIGDBL_MANT_DIGLDBL_MANT_DIG
      		 number of base-FLT_RADIX digits that are in the floating-point mantissa and that can be represented without losing precision for float, double and longdouble respectively
      (macro constant)
      FLT_MIN_EXPDBL_MIN_EXPLDBL_MIN_EXP
      		 minimum negative integer such that FLT_RADIX raised by power one less than that integer is a normalized float, double and longdouble respectively
      (macro constant)
      FLT_MIN_10_EXPDBL_MIN_10_EXPLDBL_MIN_10_EXP
      		 minimum negative integer such that 10 raised to that power is a normalized float, double and longdouble respectively
      (macro constant)
      FLT_MAX_EXPDBL_MAX_EXPLDBL_MAX_EXP
      		 maximum positive integer such that FLT_RADIX raised by power one less than that integer is a representable finite float, double and longdouble respectively
      (macro constant)
      FLT_MAX_10_EXPDBL_MAX_10_EXPLDBL_MAX_10_EXP
      		 maximum positive integer such that 10 raised to that power is a representable finite float, double and longdouble respectively
      (macro constant)
      		 rounding mode of floating-point arithmetic
      (macro constant)
      (C99)
      		 specifies in what precision all arithmetic operations are done
      (macro constant)
      FLT_HAS_SUBNORMDBL_HAS_SUBNORMLDBL_HAS_SUBNORM
      (C11)(deprecated in C23)
      		 whether the type supports subnormal (denormal) numbers:
      -1 – indeterminable, ​0​ – absent, 1 – present
      (macro constant)

      [edit]Example

      Run this code
      #include <float.h>#include <math.h>#include <stdio.h>   int main(void){printf("DECIMAL_DIG = %d\n", DECIMAL_DIG);printf("FLT_DECIMAL_DIG = %d\n", FLT_DECIMAL_DIG);printf("FLT_RADIX = %d\n", FLT_RADIX);printf("FLT_MIN = %e\n", FLT_MIN);printf("FLT_MAX = %e\n", FLT_MAX);printf("FLT_EPSILON = %e\n", FLT_EPSILON);printf("FLT_DIG = %d\n", FLT_DIG);printf("FLT_MANT_DIG = %d\n", FLT_MANT_DIG);printf("FLT_MIN_EXP = %d\n", FLT_MIN_EXP);printf("FLT_MIN_10_EXP = %d\n", FLT_MIN_10_EXP);printf("FLT_MAX_EXP = %d\n", FLT_MAX_EXP);printf("FLT_MAX_10_EXP = %d\n", FLT_MAX_10_EXP);printf("FLT_ROUNDS = %d\n", FLT_ROUNDS);printf("FLT_EVAL_METHOD = %d\n", FLT_EVAL_METHOD);printf("FLT_HAS_SUBNORM = %d\n", FLT_HAS_SUBNORM);}

      Possible output: 

      DECIMAL_DIG = 37 FLT_DECIMAL_DIG = 9 FLT_RADIX = 2 FLT_MIN = 1.175494e-38 FLT_MAX = 3.402823e+38 FLT_EPSILON = 1.192093e-07 FLT_DIG = 6 FLT_MANT_DIG = 24 FLT_MIN_EXP = -125 FLT_MIN_10_EXP = -37 FLT_MAX_EXP = 128 FLT_MAX_10_EXP = 38 FLT_ROUNDS = 1 FLT_EVAL_METHOD = 1 FLT_HAS_SUBNORM = 1

      [edit]References

      • C23 standard (ISO/IEC 9899:2024):
      • 5.2.4.2 Numerical limits (p: TBD)
      • 7.22.3 Limits of other integer types (p: TBD)
      • C17 standard (ISO/IEC 9899:2018):
      • 5.2.4.2 Numerical limits (p: 20-27)
      • 7.20.3 Limits of other integer types (p: 215-216)
      • C11 standard (ISO/IEC 9899:2011):
      • 5.2.4.2 Numerical limits (p: 26-34)
      • 7.20.3 Limits of other integer types (p: 293-294)
      • C99 standard (ISO/IEC 9899:1999):
      • 5.2.4.2 Numerical limits (p: 21-28)
      • 7.18.3 Limits of other integer types (p: 259-260)
      • C89/C90 standard (ISO/IEC 9899:1990):
      • 2.2.4.2 Numerical limits

      [edit]See also

      C++ documentation for C numeric limits interface
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