Compilare: user.cpp: In function ‘int main()’: user.cpp:96:9: warning: unused variable ‘i’ [-Wunused-variable] int i,j,p,q,op; ^ user.cpp:96:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,p,q,op; ^ user.cpp: In constructor ‘instream::instream(const char*)’: user.cpp:12:44: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer,SIZE,1,input_file); ^ user.cpp: In member function ‘void instream::advance()’: user.cpp:34:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer,SIZE,1,input_file); ^