abs, labs, llabs, imaxabs

< c‎ | numeric‎ | math
 
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abslabsllabsimaxabs
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Macro constants
 
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

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)