floor, floorf, floorl

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Error handling
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Concurrency support(C11)
Technical Specifications
Symbol index

[edit]

Numerics

Common mathematical functions
Floating-point environment(C99)
Pseudo-random number generation
Complex number arithmetic(C99)
Type-generic math(C99)
Bit manipulation(C23)
Checked integer arithmetic(C23)

[edit]

Common mathematical functions

Functions

Basic operations

abslabsllabsimaxabs (C99)(C99)
fabs
divldivlldivimaxdiv (C99)(C99)

fmod
remainder (C99)
remquo (C99)
fma (C99)
fdim (C99)
nannanfnanlnandN (C99)(C99)(C99)(C23)

Maximum/minimum operations

fmax (C99)
fmin (C99)
fmaximum (C23)
fminimum (C23)
fmaximum_mag (C23)

fmaximum_num (C23)
fminimum_mag (C23)
fminimum_num (C23)
fmaximum_mag_num (C23)
fminimum_mag_num (C23)

Exponential functions

exp
exp10 (C23)
exp2 (C99)
expm1 (C99)
exp10m1 (C23)
exp2m1 (C23)

log
log10
log2 (C99)
log1plogp1 (C99)(C23)
log10p1 (C23)
log2p1 (C23)

Power functions

sqrt
cbrt (C99)
rootn (C23)
rsqrt (C23)

hypot (C99)
compound (C23)
pow
pown (C23)
powr (C23)

Trigonometric and hyperbolic functions

sin
cos
tan
asin
acos
atan
atan2
sinpi (C23)
cospi (C23)
tanpi (C23)

asinpi (C23)
acospi (C23)
atanpi (C23)
atan2pi (C23)
sinh
cosh
tanh
asinh (C99)
acosh (C99)
atanh (C99)

Nearest integer floating-point

ceil
floor
roundlroundllround (C99)(C99)(C99)
roundeven (C23)
trunc (C99)

nearbyint (C99)
rintlrintllrint (C99)(C99)(C99)
fromfpfromfpxufromfpufromfpx (C23)(C23)(C23)(C23)

Floating-point manipulation

ldexp
frexp
scalbnscalbln (C99)(C99)
ilogbllogb (C99)(C23)
logb (C99)

modf
nextafternexttoward (C99)(C99)
nextupnextdown (C23)(C23)
copysign (C99)
canonicalize (C23)

Narrowing operations

fadd (C23)
fsub (C23)
fmul (C23)

fdiv (C23)
ffma (C23)
fsqrt (C23)

Quantum and quantum exponent

quantizedN (C23)
quantumdN (C23)

samequantumdN (C23)
llquantexpdN (C23)

Decimal re-encoding functions

encodedecdN (C23)
decodedecdN (C23)

encodebindN (C23)
decodebindN (C23)

Total order and payload functions

totalorder (C23)
getpayload (C23)

setpayload (C23)
setpayloadsig (C23)

Classification

fpclassify (C99)
iscanonical (C23)
isfinite (C99)
isinf (C99)
isnan (C99)
isnormal (C99)
signbit (C99)
issubnormal (C23)
iszero (C23)

isgreater (C99)
isgreaterequal (C99)
isless (C99)
islessequal (C99)
islessgreater (C99)
isunordered (C99)
issignaling (C23)
iseqsig (C23)

Error and gamma functions

erf (C99)
erfc (C99)

lgamma (C99)
tgamma (C99)

Types

div_tldiv_tlldiv_timaxdiv_t

(C99)(C99)

float_tdouble_t (C99)(C99)
_Decimal32_t_Decimal64_t (C23)(C23)

Macro constants

Special floating-point values

HUGE_VALHUGE_VALFHUGE_VALLHUGE_VALDN

(C99)(C99)(C23)

INFINITYDEC_INFINITY (C99)(C23)
NANDEC_NAN (C99)(C23)

Arguments and return values

FP_ILOGB0FP_ILOGBNAN (C99)(C99)
FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C99)(C99)(C99)(C99)(C99)

FP_LLOGB0FP_LLOGBNAN (C23)(C23)
FP_INT_UPWARDFP_INT_DOWNWARDFP_INT_TOWARDZEROFP_INT_TONEARESTFROMZEROFP_INT_TONEAREST (C23)(C23)(C23)(C23)(C23)

Error handling

MATH_ERRNOMATH_ERRNOEXCEPT

(C99)(C99)

math_errhandling (C99)

Fast operation indicators

FP_FAST_FMAFFP_FAST_FMA (C99)(C99)
FP_FAST_FADDFP_FAST_FADDLFP_FAST_DADDLFP_FAST_DMADDDN (C23)(C23)(C23)(C23)
FP_FAST_FMULFP_FAST_FMULLFP_FAST_DMULLFP_FAST_DMMULDN (C23)(C23)(C23)(C23)
FP_FAST_FFMAFP_FAST_FFMALFP_FAST_DFMALFP_FAST_DMFMADN (C23)(C23)(C23)(C23)

FP_FAST_FMALFP_FAST_FMADN (C99)(C23)
FP_FAST_FSUBFP_FAST_FSUBLFP_FAST_DSUBLFP_FAST_DMSUBDN (C23)(C23)(C23)(C23)
FP_FAST_FDIVFP_FAST_FDIVLFP_FAST_DDIVLFP_FAST_DMDIVDN (C23)(C23)(C23)(C23)
FP_FAST_FSQRTFP_FAST_FSQRTLFP_FAST_DSQRTLFP_FAST_DMSQRTDN (C23)(C23)(C23)(C23)

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Defined in header`<math.h>`
float floorf(float arg);	(1)	(since C99)
double floor(double arg);	(2)
longdouble floorl(longdouble arg);	(3)	(since C99)
Defined in header`<tgmath.h>`
#define floor( arg )	(4)	(since C99)

1-3) Computes the largest integer value not greater thanarg.

4) Type-generic macro: Ifarg has typelongdouble,floorl is called. Otherwise, ifarg has integer type or the typedouble,floor is called. Otherwise,floorf is called.

[edit]Parameters

arg

floating-point value

[edit]Return value

If no errors occur, the largest integer value not greater thanarg, that is⌊arg⌋, is returned.

Return value

Argument

[edit]Error handling

Errors are reported as specified inmath_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559):

The currentrounding mode has no effect.
Ifarg is ±∞, it is returned, unmodified.
Ifarg is ±0, it is returned, unmodified.
Ifarg is NaN, NaN is returned.

[edit]Notes

FE_INEXACT may be (but isn't required to be) raised when rounding a non-integer finite value.

The largest representable floating-point values are exact integers in all standard floating-point formats, so this function never overflows on its own; however the result may overflow any integer type (includingintmax_t), when stored in an integer variable.

[edit]Example

Run this code

#include <math.h>#include <stdio.h> int main(void){printf("floor(+2.7) = %+.1f\n", floor(2.7));printf("floor(-2.7) = %+.1f\n", floor(-2.7));printf("floor(-0.0) = %+.1f\n", floor(-0.0));printf("floor(-Inf) = %+f\n",   floor(-INFINITY));}

Possible output:

floor(+2.7) = +2.0floor(-2.7) = -3.0floor(-0.0) = -0.0floor(-Inf) = -inf

[edit]References

C23 standard (ISO/IEC 9899:2024):

7.12.9.2 The floor functions (p: TBD)

7.25 Type-generic math <tgmath.h> (p: TBD)

F.10.6.2 The floor functions (p: TBD)

C17 standard (ISO/IEC 9899:2018):

7.12.9.2 The floor functions (p: TBD)

7.25 Type-generic math <tgmath.h> (p: TBD)

F.10.6.2 The floor functions (p: TBD)

C11 standard (ISO/IEC 9899:2011):

7.12.9.2 The floor functions (p: 251)

7.25 Type-generic math <tgmath.h> (p: 373-375)

F.10.6.2 The floor functions (p: 526)

C99 standard (ISO/IEC 9899:1999):

7.12.9.2 The floor functions (p: 232)

7.22 Type-generic math <tgmath.h> (p: 335-337)

F.9.6.2 The floor functions (p: 463)

C89/C90 standard (ISO/IEC 9899:1990):

4.5.6.3 The floor function

[edit]See also

ceilceilfceill (C99)(C99)	computes smallest integer not less than the given value (function)[edit]
trunctruncftruncl (C99)(C99)(C99)	rounds to nearest integer not greater in magnitude than the given value (function)[edit]
roundroundfroundllroundlroundflroundlllroundllroundfllroundl (C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)	rounds to nearest integer, rounding away from zero in halfway cases (function)[edit]
C++ documentation forfloor