foo.cc: In member function 'BigInt BigInt::Add(BigInt&)':
foo.cc:45:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |   for (int i = 0; i < a.size()||i < B.a.size(); i++)
      |                   ~~^~~~~~~~~~
foo.cc:45:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |   for (int i = 0; i < a.size()||i < B.a.size(); i++)
      |                                 ~~^~~~~~~~~~~~
foo.cc:47:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |    if (i < a.size()) t += a[i];
      |        ~~^~~~~~~~~~
foo.cc:48:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |    if (i < B.a.size()) t += B.a[i];
      |        ~~^~~~~~~~~~~~
foo.cc: In member function 'BigInt& BigInt::operator=(BigInt&)':
foo.cc:59:2: warning: no return statement in function returning non-void [-Wreturn-type]
   58 |   a = A.a;
  +++ |+  return *this;
   59 |  }
      |  ^

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