/in/foo.c: In function 'main':
/in/foo.c:6:2: error: variable-sized object may not be initialized
  int a[n]={1};//a[n]
  ^~~
/in/foo.c:6:12: warning: excess elements in array initializer
  int a[n]={1};//a[n]
            ^
/in/foo.c:6:12: note: (near initialization for 'a')