Compilare: user.cpp: In function ‘void prec()’: user.cpp:44:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 4; i < powers.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:69:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(pos < values.size() && values[pos].first < qry[i].first) ^ user.cpp:71:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos < values.size() && values[pos].first == qry[i].first) ^ user.cpp: In function ‘char nextch()’: user.cpp:14:34: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, MAXBUF, fi); ^