Compilare: user.cpp: In function ‘int main()’: user.cpp:63:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = j = 0; i < v1.size() && j < v2.size();) ^ user.cpp:63:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = j = 0; i < v1.size() && j < v2.size();) ^ user.cpp:67:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < v1.size()) v.push_back(v1[i]), ++i; ^ user.cpp:68:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < v2.size()) v.push_back(v2[j]), ++j; ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:19:43: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, SIZE, 1, input_file); ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:46:47: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, SIZE, 1, input_file); ^