case 7:
cout<<"当前图书系统信息顺序表读出: \n";
for(i=0 i<L.length i ++)
cout<<left<<setw(15)<<L.elem[i].id<<"\t"<<left
<<setw(50)<<L.elem[i].name<<"\t"<<left
<<setw(5)<<L.elem[i].price<<end1;
cout<<end1;
break;