Compilare: user.cpp:44:26: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings] ifbuffer f("easygraph.in"); ^ user.cpp: In member function ‘char ifbuffer::next()’: user.cpp:13:44: 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, BUF, in), pos = 0; ^