Compilare: user.cpp: In function ‘int main()’: user.cpp:138:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < op[i].size(); j ++) { ~~^~~~~~~~~~~~~~ user.cpp: In member function ‘char InParser::read_ch()’: user.cpp:14:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^