CSCI 270: Implementing a Singly Linked List - Prof. Sandra Huerter | Study notes Data Structures and Algorithms

CSCI 270 Example of a Client-Managed Singly Linked List

#include <iostream>

using namespace std;

struct node; // forward declaration for the structure

typedef node* nodePtr; // so I can create a typedef for a pointer to it

struct node

{

int data;

nodePtr next; // or node * next;

};

void PrintList (nodePtr first);

bool SearchList (nodePtr first, nodePtr & currPtr, nodePtr & prevPtr, int key);

int main ()

{

nodePtr first, // points to the beginning of the list

currPtr, // used in a search to point to the current node

newPtr, // used to point to a newly-created node

lastPtr, // used to point to the last node in the list

predPtr; // trails one node behind currPtr in a search

int inputData;

bool found;

// Create a list from data values input in already-sorted order so that each

// new item is added at the end of the list – no searching is necessary.

first = NULL; // so I can test later to see if first is pointing to a real node

cout << "Type a series of positive integers (in ascending order)\n"

<< "to be entered into a linked list. Type a negative integer to stop.\n";

cout << "Values may be typed one per line or all on the same line.\n";

cout << "The resulting list is displayed after each value is added.\n";

cout << "Sample input: 8 10 15 25 -1\n";

cin >> inputData;

while (inputData >= 0) // for each valid input value:

{

newPtr = new node; // Create a new structure

newPtr->data = inputData; // and assign its data value.

newPtr->next = NULL; // Make new node the end of the list.

if (first == NULL) // If this is the first node in the list,

first = newPtr; // make first point to it;

else // otherwise make the previous node point

lastPtr->next = newPtr; // to this one.

lastPtr = newPtr; // Remember where the last node is.

PrintList(first); // Display list to be sure it's correct.

cin >> inputData; // get next value to be inserted into list

}

// Now let's add some nodes given to us in random order

cout << "Type one or more positive integers to be added to the list,\n";

cout << "typing -1 to stop. The new list is displayed after each entry.\n";

cout << "You can add new values or delete existing ones.\n";

cin >> inputData;

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CSCI 270 Example of a Client-Managed Singly Linked List

#include using namespace std; struct node; // forward declaration for the structure typedef node* nodePtr; // so I can create a typedef for a pointer to it struct node { int data; nodePtr next; // or node * next; }; void PrintList (nodePtr first); bool SearchList (nodePtr first, nodePtr & currPtr, nodePtr & prevPtr, int key); int main () { nodePtr first, // points to the beginning of the list currPtr, // used in a search to point to the current node newPtr, // used to point to a newly-created node lastPtr, // used to point to the last node in the list predPtr; // trails one node behind currPtr in a search int inputData; bool found; // Create a list from data values input in already-sorted order so that each // new item is added at the end of the list – no searching is necessary. first = NULL; // so I can test later to see if first is pointing to a real node cout << "Type a series of positive integers (in ascending order)\n" << "to be entered into a linked list. Type a negative integer to stop.\n"; cout << "Values may be typed one per line or all on the same line.\n"; cout << "The resulting list is displayed after each value is added.\n"; cout << "Sample input: 8 10 15 25 -1\n"; cin >> inputData; while (inputData >= 0) // for each valid input value: { newPtr = new node; // Create a new structure newPtr->data = inputData; // and assign its data value. newPtr->next = NULL; // Make new node the end of the list. if (first == NULL) // If this is the first node in the list, first = newPtr; // make first point to it; else // otherwise make the previous node point lastPtr->next = newPtr; // to this one. lastPtr = newPtr; // Remember where the last node is. PrintList(first); // Display list to be sure it's correct. cin >> inputData; // get next value to be inserted into list } // Now let's add some nodes given to us in random order cout << "Type one or more positive integers to be added to the list,\n"; cout << "typing -1 to stop. The new list is displayed after each entry.\n"; cout << "You can add new values or delete existing ones.\n"; cin >> inputData;

while (inputData >= 0) // stop when a negative value is entered { found = SearchList(first, currPtr, predPtr, inputData); if (! found) // Node isn't there, so add it. currPtr is pointing at the { // node which will follow this one, and predPtr points to // the node which will precede this node newPtr = new node; // Create a new node. newPtr->data = inputData; newPtr->next = currPtr; // This node points to next one in order. if (currPtr == first) // This will be the new first node first = newPtr; // so make head point to this node; else // otherwise, make the previous node point predPtr->next = newPtr; // to this one. } else // Delete it. currPtr is pointing at it; predPtr points at the node { // before it (or is NULL if we're deleting the first node). if (first == currPtr) // If first node is to be deleted, first = currPtr->next; // make head point to the second node. else // else , make previous node point to the predPtr->next = currPtr->next; // one after this one. delete currPtr; // Get rid of this node. } PrintList(first); cout << "Next number: "; cin >> inputData; } // end of while more data system(“pause”); return 0; } // end of main bool SearchList (nodePtr first, nodePtr & currPtr, nodePtr & predPtr, int key) { currPtr = first; // Set currPtr to point to the first node. predPtr = NULL; // predPtr will track one node behind it; while (currPtr != NULL) // While there are more nodes to look at: { if (currPtr->data == key) // if this is the one we want, stop searching return true; // and report back that we found it. if (currPtr->data > key) // If this value is greater, then the return false; // one we want isn't here, so stop searching. predPtr = currPtr; // Otherwise advance to the next node. currPtr = currPtr->next; } // If loop ended without returning, then the return false; // value we're searching for isn't there but } // logically belongs at the end of the list

Here's a sample run of the program (with user entries in bold print): Type a series of positive integers (in ascending order) to be entered into a linked list. Type a negative integer to stop. Values may be typed one per line or all on the same line. The resulting list is displayed after each value is added. Sample input: 8 10 15 25 - 5 10 15 20 25 - The list contains: 5 The list contains: 5 -> 10 The list contains: 5 -> 10 -> 15 The list contains: 5 -> 10 -> 15 -> 20 The list contains: 5 -> 10 -> 15 -> 20 -> 25 Type one or more positive integers to be added to the list, typing -1 to stop. The new list is displayed after each entry. You can add new values or delete existing ones. 16 The list contains: 5 -> 10 -> 15 -> 16 -> 20 -> 25 Next number: 3 The list contains: 3 -> 5 -> 10 -> 15 -> 16 -> 20 -> 25 Next number: 42 The list contains: 3 -> 5 -> 10 -> 15 -> 16 -> 20 -> 25 -> 42 Next number: 17 The list contains: 3 -> 5 -> 10 -> 15 -> 16 -> 17 -> 20 -> 25 -> 42 Next number: 10 The list contains: 3 -> 5 -> 15 -> 16 -> 17 -> 20 -> 25 -> 42 Next number: 3 The list contains: 5 -> 15 -> 16 -> 17 -> 20 -> 25 -> 42 Next number: 42 The list contains: 5 -> 15 -> 16 -> 17 -> 20 -> 25 Next number: 16 The list contains: 5 -> 15 -> 17 -> 20 -> 25 Next number: 17 The list contains: 5 -> 15 -> 20 -> 25 Next number: 10 The list contains: 5 -> 10 -> 15 -> 20 -> 25

CSCI 270: Implementing a Singly Linked List - Prof. Sandra Huerter, Study notes of Data Structures and Algorithms

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CSCI 270 Example of a Client-Managed Singly Linked List