bsd man page for abs

ABS(3)							     Library Functions Manual							    ABS(3)

NAME
       abs - integer absolute value

SYNOPSIS
       abs(i)
       int i;

DESCRIPTION
       Abs returns the absolute value of its integer operand.

SEE ALSO
       floor(3M) for fabs

BUGS
       Applying the abs function to the most negative integer generates a result which is the most negative integer.  That is,

       abs(0x80000000)

       returns 0x80000000 as a result.

7th Edition							   May 15, 1985 							    ABS(3)