Материал из C\C++ эксперт
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The header float.h in the C Standard Library for the C programming language contains macros that expand to various limits and parameters of the standard floating-point types.
The macros, as defined on ISO 9899:1999 section 5.2.4.2.2, are:
- FLT_ROUNDS - indicates the rounding mode for floating-point addition, meaning:
- -1 indeterminable;
- 0 toward zero;
- 1 to nearest;
- 2 toward positive infinity;
- 3 toward negative infinity;
- other value means implementation-defined rounding behavior.
- FLT_EVAL_METHOD - determines the evaluation formats of expressions involving all floating types:
- -1 indeterminable;
- 0 evaluate all operations and constants just to the precision of the type;
- 1 evaluate operations and constants of type float and double to the range and precision of the double type;
- 2 evaluate all operations and constants to the range and precision of the long double type;
- other value means implementation-defined behavior.
- FLT_RADIX - radix of exponent representation (at least 2).
- FLT_MANT_DIG, DBL_MANT_DIG, LDBL_MANT_DIG - number of digits in the floating-point significand.
- DECIMAL_DIG - (at least 10)
- FLT_DIG, DBL_DIG, LDBL_DIG - (at least 6, 10, 10)
- FLT_MIN_EXP, DBL_MIN_EXP, LDBL_MIN_EXP
- FLT_MIN_10_EXP, DBL_MIN_10_EXP, LDBL_MIN_10_EXP, (at least -37)
- FLT_MAX_EXP, DBL_MAX_EXP, LDBL_MAX_EXP
- FLT_MAX_10_EXP, DBL_MAX_10_EXP, LDBL_MAX_10_EXP (at least +37)
- FLT_MAX, DBL_MAX, LDBL_MAX - (at least 1E+37)
- FLT_EPSILON, DBL_EPSILON, LDBL_EPSILON - (at least 1E-5, 1E-9, 1E-9)
- FLT_MIN, DBL_MIN, LDBL_MIN - (at least 1E-37)
