abs

int        abs( int n );

long       labs( long n );

long long llabs( long long n );

intmax_t imaxabs( intmax_t n );

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

Parameters

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 <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
}

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