/in/foo.cc: In function 'void mul(BigInt*, int)':
/in/foo.cc:13:33: warning: 'jw' may be used uninitialized in this function [-Wmaybe-uninitialized]
   p->digit[i] = p->digit[i] * x + jw;
                 ~~~~~~~~~~~~~~~~^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:13:33: warning: 'jw' may be used uninitialized in this function [-Wmaybe-uninitialized]
   p->digit[i] = p->digit[i] * x + jw;
                 ~~~~~~~~~~~~~~~~^~~~
/in/foo.cc:11:6: note: 'jw' was declared here
  int jw;
      ^~
/in/foo.cc:13:33: warning: 'jw' may be used uninitialized in this function [-Wmaybe-uninitialized]
   p->digit[i] = p->digit[i] * x + jw;
                 ~~~~~~~~~~~~~~~~^~~~
/in/foo.cc:11:6: note: 'jw' was declared here
  int jw;
      ^~