Compilare: user.cpp: In function ‘int main()’: user.cpp:112:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < vec[i].size(); j++) { ^ user.cpp: In function ‘char nextch()’: user.cpp:16:34: 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); ^