Compilare: user.cpp: In function ‘int main()’: user.cpp:73:13: warning: unused variable ‘l’ [-Wunused-variable] int i,j,l,c; ^ user.cpp:73:15: warning: unused variable ‘c’ [-Wunused-variable] int i,j,l,c; ^ user.cpp: In member function ‘void instream::advance()’: user.cpp:49:44: 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:18:40: 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); ^