单项选择题

执行语句序列 ofstream outfite("data.dat"); if(...)cout<<"ok";else cout<<"fail"; 后,如果文件打开成功,显示“ok”,否则显示“fail”。由此可知,上面if语句的“…”处的表达式是

A.outfilfail()或outfile
B.outfilgood()或!outfile
C.outfilgood()或outfile
D.outfilfail()或!outfile