/in/foo.cc: In function 'int main()':
/in/foo.cc:48:15: warning: unused variable 'start' [-Wunused-variable]
  int i,n,a[N],start,end;
               ^~~~~
/in/foo.cc:48:21: warning: unused variable 'end' [-Wunused-variable]
  int i,n,a[N],start,end;
                     ^~~
/in/foo.cc: In function 'void quickSort(int*, int, int)':
/in/foo.cc:41:16: warning: 'pos' may be used uninitialized in this function [-Wmaybe-uninitialized]
   pos = segment(a,start,pos - 1);
         ~~~~~~~^~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:41:16: warning: 'pos' may be used uninitialized in this function [-Wmaybe-uninitialized]
   pos = segment(a,start,pos - 1);
         ~~~~~~~^~~~~~~~~~~~~~~~~
/in/foo.cc:38:6: note: 'pos' was declared here
  int pos;
      ^~~