foo.c: In function 'main':
foo.c:6:9: warning: statement with no effect [-Wunused-value]
    6 |         for(i;i<7;i++) {
      |         ^~~
foo.c:3:13: warning: unused variable 'arr' [-Wunused-variable]
    3 |         int arr[7];
      |             ^~~

[Hydro](https://hydro.ac)提供评测服务