Numeric limits - cppreference.com (original) (raw)

Contents

[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 signed char, short, int, long, and long long respectively (macro constant)
SCHAR_MINSHRT_MININT_MINLONG_MINLLONG_MIN(C99) minimum value of signed char, short, int, long and long long respectively (macro constant) [edit]
SCHAR_MAXSHRT_MAXINT_MAXLONG_MAXLLONG_MAX(C99) maximum value of signed char, short, int, long and long long respectively (macro constant) [edit]
UCHAR_WIDTHUSHRT_WIDTHUINT_WIDTHULONG_WIDTHULLONG_WIDTH(C23)(C23)(C23)(C23)(C23) bit width of unsigned char, unsigned short, unsigned int, unsigned long, and unsigned long long respectively (macro constant)
UCHAR_MAXUSHRT_MAXUINT_MAXULONG_MAXULLONG_MAX(C99) maximum value of unsigned char, unsigned short, unsigned int,unsigned long and unsigned long long 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 unsigned int, 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

#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 long double to decimal with at least DECIMAL_DIG digits and back to long double is the identity conversion: this is the decimal precision required to serialize/deserialize a long double (macro constant)
FLT_DECIMAL_DIGDBL_DECIMAL_DIGLDBL_DECIMAL_DIG(C11) conversion from float/double/long double 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 long double respectively (macro constant)
FLT_TRUE_MINDBL_TRUE_MINLDBL_TRUE_MIN(C11) minimum positive value of float, double and long double respectively (macro constant)
FLT_MAXDBL_MAXLDBL_MAX maximum finite value of float, double and long double respectively (macro constant)
FLT_EPSILONDBL_EPSILONLDBL_EPSILON absolute value difference between 1.0 and the next representable value for float, double and long double respectively (macro constant)
FLT_DIGDBL_DIGLDBL_DIG number of decimal digits that are guaranteed to be preserved in text → float/double/long double → 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 long double 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 long double 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 long double 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 long double 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 long double respectively (macro constant)
FLT_ROUNDS rounding mode of floating-point arithmetic (macro constant)
FLT_EVAL_METHOD(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

#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

[edit] See also