abs, labs, llabs, imaxabs

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Common mathematical functions
Types
Functions
Basic operations
abs labs llabs imaxabs
(C99) (C99)
(C99)
(C99)
(C99)
(C99) (C99) (C99) (C23)
Maximum/minimum operations
Exponential functions
Power functions
Trigonometric and hyperbolic functions
Error and gamma functions
(C99)
(C99)
(C99)
(C99)
Nearest integer floating-point operations
(C99) (C99) (C99)
(C23) (C23) (C23) (C23)
Floating-point manipulation functions
Narrowing operations
(C23)
(C23)
(C23)
(C23)
(C23)
(C23)
Quantum and quantum exponent functions
Decimal re-encoding functions
Total order and payload functions
Classification
Macro constants
Special floating-point values
Arguments and return values
Error handling
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

#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) = 3
abs(-3) = 3

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

See also

(C99) (C99)
computes absolute value of a floating-point value ( |x| )
(function)
(C99) (C99) (C99)
computes the magnitude of a complex number
(function)