C++课程设计（10个经典例子）

/*第5题 电话簿管理--源代码及关键源代码注解如下：*/ //PhoneBook 1.0 By Mark Miller //compiler directives #include<fstream.h> #include<conio.h> #include<iostream.h> #include<iomanip.h> #include<string.h> #include<stdlib.h> //global structures and variables struct friend_node //结构体类型定义，包括：姓、名和电话号码 { char last_name[20]; char first_name[15]; char phone_num[12]; friend_node *next; }; friend_node *head_ptr; //全程变量，链头指针 friend_node *current_ptr; //全程变量，用于指明当前在链表中的位置 //function prototypes void handle_choice(int choice); //--函数原形说明 void add_record(); void insert_node(friend_node *new_rec_ptr); friend_node *position_insertion_point(char lastname[20]); void make_node_new_head(friend_node *new_rec_ptr); void add_node_to_end(friend_node *new_rec_ptr); void move_current_to_end(); void display_list(); void delete_record(); void delete_head_of_list(); void delete_end_of_list(friend_node *previous_ptr); void delete_from_middle_of_list(friend_node *previous_ptr); int verify_delete(); void delete_node(friend_node *previous_ptr); void delete_list(); void search_by_lastname(); void write_list_to_file(); void load_list_from_file(); void help_me(); char pause; //main function int main() { cout << "Welcome to PhoneBook 1.0 for dos and freedos\n"; cout << "Press Enter To Continue\n"; cin.get(pause); system("cls"); //执行系统命令：cls-清屏 int choice; head_ptr = NULL; // Initialize head pointer to NULL. load_list_from_file(); // Load data from the disk file into linked list. do { // Display menu.-- 主菜单显示 cout << "1 - Add record\n"; cout << "2 - Display all records\n"; cout << "3 - Search for friend by last name\n"; cout << "4 - Delete record\n"; cout << "5 - Help\n"; cout << "6 - Exit program\n"; cout << "Enter choice: "; cin >> choice; handle_choice(choice); // Call function to direct flow based on choice. } while(choice != 6); // Repeat menu until user chooses to exit. return 0; } // end of main function // Function to direct program flow based on user's choice. void handle_choice(int choice) // 根据用户选择（choice）调用对应处函数 { switch(choice) // choice is passed into the function by value. { case 1: // If choice was to add a record to the database, add_record(); // call function to add a record to the linked list. break; case 2: // If choice was to display all records in the database, display_list(); // call function to display all records in break; // the linked list. case 3: // If choice was to search for a record in the database, search_by_lastname(); // call function to search for record by break; // last name. case 4: // If choice was to delete a record in the database, delete_record(); // call a function that searched for record break; // by last name and deletes it. case 5: // If choice is for help help_me(); break; case 6: // If choice was to exit, write_list_to_file(); // save database to a file and if(head_ptr != NULL) // delete the list from memory. { delete_list(); } break; default : // If any other (invalid) choice was entered, cout <<"Invalid choice\n"; // display error message. break; } } // end of function handle_choice // Function to add record to the linked list. void add_record() // 在链表中增加一个记录 { friend_node *new_rec_ptr; // Declare temporary pointer for the new node. new_rec_ptr = new friend_node; // Allocate memory for a new node and // initialize pointer to point to it. if(new_rec_ptr != NULL) // If no error allocating memory, get data { system("cls"); // and insert node. // Get name and phone number from the user. cin.ignore(20,'\n'); cout << "First Name: "; cin.get(new_rec_ptr->first_name,15); cin.ignore(20,'\n'); cout << "Last Name: "; cin.get(new_rec_ptr->last_name,20); cin.ignore(20,'\n'); cout << "Phone Number: "; cin.get(new_rec_ptr->phone_num,15); cin.ignore(20,'\n'); insert_node(new_rec_ptr); } else // If error occurred allocating memory, display warning { // and do not create node. cout << "WARNING: Memory error. New record cannot be added.\n"; }system("cls"); } // end of function add_record // Function to insert new node into correct position in list. void insert_node(friend_node *new_rec_ptr) //将一个由new_rec_ptr 指向的新节点插入链表中 { system("cls"); friend_node *before_ptr; friend_node *after_ptr; if(head_ptr == NULL) { // If no nodes exist, make the node new_rec_ptr->next = NULL; // the head. head_ptr = new_rec_ptr; } else { if(strcmp(new_rec_ptr->last_name, head_ptr->last_name) < 0) { // If new record comes before head, make_node_new_head(new_rec_ptr); // make it the new head. } else // Else, determine where the new node { // should be inserted. current_ptr = position_insertion_point(new_rec_ptr->last_name); before_ptr = current_ptr; // Use pointers to keep track of nodes after_ptr = current_ptr->next; // on each side of the insertion point. if(after_ptr == NULL) // If after_ptr is NULL, the node needs to be { // added to the end of the list. add_node_to_end(new_rec_ptr); } else // Else add the node between the nodes pointed to { // by before_ptr and after_ptr. before_ptr->next = new_rec_ptr; new_rec_ptr->next = after_ptr; } } } } // end of function insert_node // Function that positions current_ptr at the node before the position // where the new node should be inserted. friend_node *position_insertion_point(char lastname[20]) { // 根据姓氏，返回其在链表中的正确位置。新节点即将插入此点。 char temp_name[20]; friend_node *temp_ptr; int tempint; if(head_ptr->next != NULL) // If more than one node exists, search the { // list for the correct insertion point. current_ptr = head_ptr; temp_ptr = current_ptr->next; strcpy(temp_name, temp_ptr->last_name); // Loop until the proper insertion point is located. tempint = strcmp(lastname,temp_name); while((tempint > 0) && (current_ptr->next !=NULL)) { current_ptr = temp_ptr; // check to see if the current node is the last node if(current_ptr->next != NULL) { temp_ptr = current_ptr->next; strcpy(temp_name, temp_ptr->last_name); tempint = strcmp(lastname,temp_name); } } } else // If only one node exists in the list, current_ptr is the same { // as head_ptr. New node will be added to the end of the list. current_ptr = head_ptr; } return(current_ptr); } // end of function position_insertion_point // Function that makes the node pointed to by new_rec_ptr the new // head of the linked list. It handles the special case of inserting at // the front of the list. void make_node_new_head(friend_node *new_rec_ptr) { friend_node *temp_ptr; // temporary pointer to keep track of the head temp_ptr = head_ptr; // Set temp_ptr to point at the current head. new_rec_ptr->next = temp_ptr; // Make new nodes next pointer point to head_ptr = new_rec_ptr; // current head and make new node the head. } // end of function make_node_new_head // Function that adds a node to the end of the linked list. It handles // the special case of inserting at the end of the list. void add_node_to_end(frie