Data Structures 02 - Singly Linked List

Code Display

#include <stdio.h>
#include <malloc.h>

/**
 * Character linked list node structure. The key data is data.
 */
typedef struct LinkNode{
	char data;
	struct LinkNode *next;
} LNode, *LinkList, *NodePtr;

/**
 * Initialize the linked list and create a head node.
 * @return Pointer to the head node.
 */
LinkList initLinkList(){
	NodePtr tempHeader = (NodePtr)malloc(sizeof(LNode));
	tempHeader->data = '\0';
	tempHeader->next = NULL;
	return tempHeader;
}// End of initLinkList

/**
 * Print the linked list.
 * @param paraHeader The head node of the linked list.
 */
void printList(NodePtr paraHeader){
	NodePtr p = paraHeader->next;
	while (p != NULL) {
		printf("%c", p->data);
		p = p->next;
	}// End of loop
	printf("\r\n");
}// End of printList

/**
 * Print the linked list and its memory information.
 * @param paraHeader The head node of the linked list.
 */
void printListMemory(NodePtr paraHeader){
	NodePtr p = paraHeader;
	while (p != NULL) {
	    printf("At address %ld, data = %c, next = %ld \r\n", p, p->data, p->next);
		p = p->next;
	}// End of loop
	printf("\r\n");
}// End of printListMemory


/**
 * Append an element to the end of the linked list.
 * @param paraHeader The head node of the linked list.
 * @param paraChar The character to append.
 */
void appendElement(NodePtr paraHeader, char paraChar){
	NodePtr p, q;

	// Step 1: Construct a new node.
	q = (NodePtr)malloc(sizeof(LNode));
	q->data = paraChar;
	q->next = NULL;

	// Step 2: Search to the end.
	p = paraHeader;
	while (p->next != NULL) {
		p = p->next;
	}// End of loop

	// Step 3: Link the new node.
	p->next = q;
}// End of appendElement

/**
 * Insert an element at the specified position.
 * @param paraHeader The head node of the linked list.
 * @param paraChar The character to insert.
 * @param paraPosition The specified position.
 */
void insertElement(NodePtr paraHeader, char paraChar, int paraPosition){
	NodePtr p, q;

	// Step 1: Search to the specified position.
	p = paraHeader;
	for (int i = 0; i < paraPosition; i ++) {
		p = p->next;
		if (p == NULL) {
			printf("Position %d is beyond the scope of the list.", paraPosition);
			return;
		}// If null, return
	} // End of for loop

	// Step 2: Construct a new node.
	q = (NodePtr)malloc(sizeof(LNode));
	q->data = paraChar;

	// Step 3: Insert the new node.
	printf("Linking\r\n");
	q->next = p->next;
	p->next = q;
}// End of insertElement

/**
 * Delete an element from the linked list.
 * @param paraHeader The head node of the linked list.
 * @param paraChar The character to delete.
 */
void deleteElement(NodePtr paraHeader, char paraChar){
	NodePtr p, q;
	p = paraHeader;
	while ((p->next != NULL) && (p->next->data != paraChar)){
		p = p->next;
	}// End of loop

	if (p->next == NULL) {
		printf("Cannot delete character %c\r\n", paraChar);
		return;
	}// If null, return

	q = p->next;
	p->next = p->next->next;
	free(q);
}// End of deleteElement

/**
 * Unit test.
 */
void appendInsertDeleteTest(){
	// Step 1: Initialize an empty linked list.
	LinkList tempList = initLinkList();
	printList(tempList);

	// Step 2: Append some characters.
	appendElement(tempList, 'H');
	appendElement(tempList, 'e');
	appendElement(tempList, 'l');
	appendElement(tempList, 'l');
	appendElement(tempList, 'o');
	appendElement(tempList, '!');
	printf("After appending elements");
	printList(tempList);
	printListMemory(tempList);

	// Step 3: Delete some characters (first occurrence).
	deleteElement(tempList, 'e');
	deleteElement(tempList, 'a');
	deleteElement(tempList, 'o');
	printf("After deleting elements");
	printList(tempList);
	printListMemory(tempList);

	// Step 4: Insert at the specified position.
	insertElement(tempList, 'o', 1);
	printf("After inserting element");
	printList(tempList);
	printListMemory(tempList);
}// End of appendInsertDeleteTest

/**
 * Address test: a test beyond the textbook content.
 */
void basicAddressTest(){
	LNode tempNode1, tempNode2;

	tempNode1.data = 4;
	tempNode1.next = NULL;

	tempNode2.data = 6;
	tempNode2.next = NULL;

	printf("The first node: %d, %d, %d\r\n",
		&tempNode1, &tempNode1.data, &tempNode1.next);
	printf("The second node: %d, %d, %d\r\n",
		&tempNode2, &tempNode2.data, &tempNode2.next);

	tempNode1.next = &tempNode2;
}// End of basicAddressTest

/**
 * Main function entry point.
 */
int main(){
	appendInsertDeleteTest();
	return 0;
}// End of main

Running Result