Float.h

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C++ Standard Library headers
C Standard Library headers
assert.h
complex.h
ctype.h
errno.h
fenv.h
float.h
inttypes.h
iso646.h
limits.h
locale.h
math.h
setjmp.h
signal.h
stdarg.h
stdbool.h
stddef.h
stdint.h
stdio.h
stdlib.h
string.h
tgmath.h
time.h
wchar.h
wctype.h

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 behaviour.

• 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 evaulate 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)

[edit] External links

• Enquire: A program for automatically generating float.h, and for checking that the values in an existing float.h are correct