/in/foo.c: In function 'main':
/in/foo.c:13:11: warning: passing argument 1 of 'fun' makes pointer from integer without a cast [-Wint-conversion]
   sum=fun(a[n], n);
           ^
/in/foo.c:3:5: note: expected 'int *' but argument is of type 'int'
 int fun(int a[],int n);
     ^~~
/in/foo.c:7:19: warning: unused variable 'num' [-Wunused-variable]
     int a[1000],n,num,i;
                   ^~~