abs, labs, llabs, imaxabs

Functions

Basic operations

abslabsllabsimaxabs (C99)
fabs
divldivlldivimaxdiv (C99)
fmod

remainder (C99)
remquo (C99)
fma (C99)
fmax (C99)
fmin (C99)
fdim (C99)
nannanfnanl (C99)(C99)(C99)

Exponential functions

exp
exp2 (C99)
expm1 (C99)

log
log10
log1p (C99)
log2 (C99)

Power functions

sqrt
cbrt (C99)

hypot (C99)
pow

Trigonometric and hyperbolic functions

sin
cos
tan
asin
acos
atan
atan2

sinh
cosh
tanh
asinh (C99)
acosh (C99)
atanh (C99)

Error and gamma functions

erf (C99)
erfc (C99)

lgamma (C99)
tgamma (C99)

Nearest integer floating point operations

ceil
floor
roundlroundllround (C99)(C99)(C99)

trunc (C99)
nearbyint (C99)
rintlrintllrint (C99)(C99)(C99)

Floating point manipulation functions

ldexp
scalbnscalbln (C99)(C99)
ilogb (C99)
logb (C99)

frexp
modf
nextafternexttoward (C99)(C99)
copysign (C99)

Classification

fpclassify (C99)
isfinite (C99)
isinf (C99)
isnan (C99)
isnormal (C99)
signbit (C99)

isgreater (C99)
isgreaterequal (C99)
isless (C99)
islessequal (C99)
islessgreater (C99)
isunordered (C99)

Types

div_tldiv_tlldiv_timaxdiv_t

(C99)(C99)

float_tdouble_t

(C99)(C99)

Macro constants

HUGE_VALFHUGE_VALHUGE_VALL (C99)(C99)
FP_FAST_FMAFFP_FAST_FMAFP_FAST_FMAL (C99)(C99)(C99)
math_errhandlingMATH_ERRNOMATH_ERRNOEXCEPT (C99)(C99)(C99)

INFINITY (C99)
NAN (C99)
FP_ILOGB0FP_ILOGBNAN (C99)(C99)
FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C99)(C99)(C99)(C99)(C99)

Defined in header `<stdlib.h>`
int abs( int n );
long labs( long n );
long long llabs( long long 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.

Parameters

n

-

integer value

Return value

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

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 type int, INT_MIN is -2147483648, but the would-be result 2147483648 is greater than INT_MAX, which is 2147483647.

Example

Run this code

#include <stdio.h>
#include <stdlib.h>
#include <limits.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) = 3
abs(-3) = 3

References

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

Language
headers
Type support
Dynamic memory management
Error handling
Program utilities
Variadic function support
Date and time utilities
Strings library
Algorithms
Numerics
Input/output support
Localization support
Thread support (C11)
Atomic operations (C11)
Technical Specifications

Common mathematical functions
Floating-point environment
Complex number arithmetics
Random number generation
Type-generic math