foo.cc: In function 'int main()':
foo.cc:50:39: warning: statement has no effect [-Wunused-value]
   50 |                                 num[j]%10;
      |                                 ~~~~~~^~~
foo.cc:71:24: warning: 'len' may be used uninitialized [-Wmaybe-uninitialized]
   71 |                 len=div(num,k,len);
      |                     ~~~^~~~~~~~~~~
foo.cc:54:13: note: 'len' was declared here
   54 |         int len;
      |             ^~~
foo.cc:37:21: warning: 'len' may be used uninitialized [-Wmaybe-uninitialized]
   37 |                 int len;
      |                     ^~~

[Hydro](https://hydro.ac)提供评测服务