/in/foo.c: In function 'wang':
/in/foo.c:12:11: warning: 'return' with a value, in function returning void
    return max;
           ^~~
/in/foo.c:2:6: note: declared here
 void wang(float a[],int n)
      ^~~~
/in/foo.c:17:11: warning: 'return' with a value, in function returning void
    return min;
           ^~~
/in/foo.c:2:6: note: declared here
 void wang(float a[],int n)
      ^~~~
/in/foo.c:21:10: warning: 'return' with a value, in function returning void
   return ag;
          ^~
/in/foo.c:2:6: note: declared here
 void wang(float a[],int n)
      ^~~~