Compilare: user.cpp: In function ‘int main()’: user.cpp:157:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < G[offset].size(); i++){ ~~^~~~~~~~~~~~~~~~~~ user.cpp: In function ‘char nextch()’: user.cpp:11:36: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, BUF_SIZE, 1, fi); ^