The <float.h> header file


  
This header file contains a set of various platform-dependent constants (related to floating point values) proposed in ANSI C, which allow making more portable programs:

NameTypeValueMeaning
FLT_RADIXunsigned int10The base used for representing the exponent
FLT_ROUNDSunsigned int1Option for rounding floating point numbers during the addition
FLT_NORMALIZEunsigned int1Indicates that floating point numbers should always be normalized
FLT_DIG
DBL_DIG
LDBL_DIG
unsigned int16Number of significant digits in a floating point number
FLT_MANT_DIG
DBL_MANT_DIG
LDBL_MANT_DIG
unsigned int16Number of FLT_RADIX digits in the mantissa
FLT_MANT_BITS
DBL_MANT_BITS
LDBL_MANT_BITS
unsigned int64Number of bits used for the mantissa
FLT_EPSILON
DBL_EPSILON
LDBL_EPSILON
float
double
long double
1e-15The smallest x for which is 1.0+x != 1.0
FLT_MAX
DBL_MAX
LDBL_MAX
float
double
long double
9.999999999999999e999The maximal floating point value (see notes about FLT_MAX_EXP)
FLT_MIN
DBL_MIN
LDBL_MIN
float
double
long double
1e-999The minimal floating point value (see notes about FLT_MIN_EXP)
FLT_MAX_EXP
DBL_MAX_EXP
LDBL_MAX_EXP
int999The maximal exponent of a floating point value expressed in base FLT_RADIX; greater exponents are principally possible (up to 16383), but not supported in all math functions
FLT_MAX_2_EXP
DBL_MAX_2_EXP
LDBL_MAX_2_EXP
int3321The maximal exponent of a floating point value expressed in base 2 (see notes about FLT_MAX_EXP)
FLT_MAX_10_EXP
DBL_MAX_10_EXP
LDBL_MAX_10_EXP
int999The maximal exponent of a floating point value expressed in base 10 (see notes about FLT_MAX_EXP)
FLT_MIN_EXP
DBL_MIN_EXP
LDBL_MIN_EXP
int-999The maximal exponent of a floating point value expressed in base FLT_RADIX; smaller exponents are principally possible (up to -16383), but not supported in all math functions
FLT_MIN_2_EXP
DBL_MIN_2_EXP
LDBL_MIN_2_EXP
int-3318The minimal exponent of a floating point value expressed in base 2 (see notes about FLT_MIN_EXP)
FLT_MIN_10_EXP
DBL_MIN_10_EXP
LDBL_MIN_10_EXP
int-999The minimal exponent of a floating point value expressed in base 10 (see notes about FLT_MIN_EXP)


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