Compilare: user.cpp: In member function ‘BigInt BigInt::operator+(BigInt)’: user.cpp:26:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size(); i++) ^ user.cpp: In member function ‘BigInt BigInt::operator-(BigInt)’: user.cpp:42:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size(); i++) ^ user.cpp: In member function ‘BigInt BigInt::operator*(int)’: user.cpp:59:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size(); i++) ^ user.cpp: In member function ‘std::string BigInt::str()’: user.cpp:108:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] ret += (i < v.size()-1 ? std::string(basewidth-s.size(), '0') : "") + s; ^ user.cpp: In function ‘BigInt operator*(int, BigInt)’: user.cpp:119:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < b.v.size(); i++) ^