Compilare: user.cpp: In function ‘int main()’: user.cpp:106:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<z[i].size();j++) ^ user.cpp: In member function ‘void instream::advance()’: user.cpp:38:44: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer,sizy,1,input_file); ^ user.cpp: In constructor ‘instream::instream(const char*)’: user.cpp:16:40: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer,sizy,1,input_file); ^