Data Abstraction and Problem Solving with C++
Walls and Mirrors
by Frank M. Carrano
example209.cpp
Go to the documentation of this file.00001 00016 // Creates a linked list from the data in a text 00017 // file. The pointer variables head and tail are 00018 // initially NULL. fileName is a string that names 00019 // an existing external text file. 00020 00021 ifstream inFile(fileName); 00022 int nextItem; 00023 00024 if (inFile >> nextItem) // Is file empty? 00025 { // File not empty: 00026 try 00027 { head = new Node; 00028 // Add the first integer to the list. 00029 head->item = nextItem; 00030 head->next = NULL; 00031 tail = head; 00032 00033 // Add remaining integers to linked list. 00034 while (inFile >> nextItem) 00035 { tail->next = new Node; 00036 tail = tail->next; 00037 tail->item = nextItem; 00038 tail->next = NULL; 00039 } // end while 00040 } // end try 00041 catch (bad_alloc e) 00042 { throw ListException( 00043 "ListException: restore cannot allocate memory."); 00044 } // end catch 00045 } // end if 00046 00047 inFile.close(); 00048 00049 // Assertion: head points to the first node of the 00050 // created linked list; tail points to the last 00051 // node. If the file is empty, head and tail are 00052 // NULL (list is empty).
