llabs() computes the absolute value of the argument j of the appropriate integer type for the function.
Returns the absolute value of the integer argument, of the appropriate integer type for the function.
Trying to take the absolute value of the most negative integer is not defined.
The llabs() function is included in glibc since version 2.0, but is not in libc5 or libc4.
For llabs() to be declared, it may be necessary to define _ISOC99_SOURCE or _ISOC9X_SOURCE (depending on the version of glibc) before including any standard headers.
GCC 3.0 also handles llabs() as builtin.