abs, labs, llabs, imaxabs

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Compiler support
Language
Headers
Type support
Program utilities
Variadic function support
Error handling
Dynamic memory management
Strings library
Algorithms
Numerics
Date and time utilities
Input/output support
Localization support
Concurrency support(C11)
Technical Specifications
Symbol index

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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)

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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`<stdlib.h>`
int abs(int n);
long labs(long n);
longlong llabs(longlong n);		(since C99)
Defined in header`<inttypes.h>`
intmax_t imaxabs(intmax_t n);		(since C99)

Computes the absolute value of an integer number. The behavior is undefined if the result cannot be represented by the return type.

[edit]Parameters

integer value

[edit]Return value

The absolute value ofn (i.e.|n|), if it is representable.

[edit]Notes

In 2's complement systems, the absolute value of the most-negative value is out of range, e.g. for 32-bit 2's complement typeint,INT_MIN is-2147483648, but the would-be result2147483648 is greater thanINT_MAX, which is2147483647.

[edit]Example

Run this code

#include <limits.h>#include <stdio.h>#include <stdlib.h> int main(void){printf("abs(+3) = %d\n", abs(+3));printf("abs(-3) = %d\n", abs(-3)); //  printf("%+d\n", abs(INT_MIN)); // undefined behavior on 2's complement systems}

Output:

abs(+3) = 3abs(-3) = 3

[edit]References

C23 standard (ISO/IEC 9899:2024):

7.8.2.1 The imaxabs function (p: TBD)

7.22.6.1 The abs, labs and llabs functions (p: TBD)

C17 standard (ISO/IEC 9899:2018):

7.8.2.1 The imaxabs function (p: 159)

7.22.6.1 The abs, labs and llabs functions (p: 259)

C11 standard (ISO/IEC 9899:2011):

7.8.2.1 The imaxabs function (p: 218)

7.22.6.1 The abs, labs and llabs functions (p: 356)

C99 standard (ISO/IEC 9899:1999):

7.8.2.1 The imaxabs function (p: 199-200)

7.20.6.1 The abs, labs and llabs functions (p: 320)

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

4.10.6.1 The abs function

4.10.6.3 The labs function

[edit]See also

fabsfabsffabsl (C99)(C99)	computes absolute value of a floating-point value (\(\small{\|x\|}\)\|x\|) (function)[edit]
cabscabsfcabsl (C99)(C99)(C99)	computes the magnitude of a complex number (function)[edit]
C++ documentation forabs