单链表的增、删、改、查

 

单链表的增、删、改、查（原创）

 

 

由 王宇 原创并发布：

 

以下代码均在linux 环境下，gcc v4.5 编译调试通过。

 

#include <stdio.h>
#include <stdlib.h>

struct node
{
	int data;
	struct node *next;
}*head;


void append(int number)
{
	struct node *append_node = NULL, *right = NULL;

	append_node = (struct node *)malloc(sizeof(struct node));
	if(append_node == NULL)
	{
		perror("Error: memory alloced failed at function of append!");	
		exit(EXIT_FAILURE);
	}

	append_node->data = number;
	append_node->next = NULL;

	if(head == NULL)
	{
		head = append_node;	
		return;
	}

	right = head; 
	while(right->next != NULL)
	{
		right = right->next;	
	}

	right->next = append_node;
}


void add(int number)
{

	struct node *add_node = NULL;

	add_node = (struct node *)malloc(sizeof(struct node));
	if(add_node == NULL)
	{
		perror("Error: memory alloced failed at function of add!");	
		exit(EXIT_FAILURE);
	}

	add_node->data = number;
	add_node->next = NULL;

	if(head== NULL)
	{
		head = add_node;	
	}
	else
	{
		add_node->next = head;
		head = add_node;
	}

}


void insert_at(int number, int position)
{
	int i;	
	struct node *insert_node = NULL, *left = NULL, *right = NULL;

	left = head;

	if(left == NULL)
	{
	
			perror("Error: linked list wasnot created!");		
			return;
	}

	if(position < 1)
	{
			perror("Error: Did not find position!");		
			return;
	}

	for(i = 0; i < position; i++)
	{
		if(left != NULL )
		{
			if(i == position - 1)
			{
				right = left->next;	
				break;	
			}
			else
			{
				left = left->next;	
			}

		}
		else
		{
			perror("Error: Did not find position!");		
			return;
		}
	}

	insert_node = (struct node *)malloc(sizeof(struct node));
	if(insert_node == NULL)
	{
		perror("Error: memory alloced failed at function of append!");	
		exit(EXIT_FAILURE);
	}

	insert_node->data = number;
	insert_node->next = right;

	left->next = insert_node;

}


int  delete_number(int number)
{
	struct node *linked_list = NULL, *previous = NULL;
	linked_list = head;

	while (linked_list != NULL)
	{
		if(linked_list->data == number)
		{
			if(linked_list == head)
			{
				head = linked_list->next;
				free(linked_list);
				return 1;
			}
			else
			{
				previous->next = linked_list->next;	
				free(linked_list);
				return 1;

			}
		}
		else
		{
			previous = linked_list;
			linked_list = linked_list->next;
		}

	}

	return 0;
}


void delete_all()
{
	struct node *linked_list = NULL;

	linked_list = head;

	while ( head != NULL)
	{
		linked_list = head->next;
		head = head->next;
		free(linked_list);	
	}
}


void display()
{

	struct node *linked_list = NULL;

	linked_list = head;

	while ( linked_list != NULL)
	{
		printf("Data of linked list is %d \n", linked_list->data);
		linked_list = linked_list->next;
	}
}


int count_sum()
{
	int sum = 0;
	struct node *linked_list = NULL;

	linked_list = head;

	while ( linked_list != NULL)
	{
		sum++;
		linked_list = linked_list->next;
	}

	return sum;
}


int main()
{
	int i, number, position;	

	while(1)
	{
		printf("\nList Operations\n");
		printf("===============\n");
		printf("1.Create\n");
		printf("2.Add\n");
		printf("3.Append\n");
		printf("4.Insert\n");
		printf("5.Display\n");
		printf("6.Size\n");
		printf("7.Delete\n");
		printf("8.DeleteAll\n");
		printf("0.Exit\n");
		printf("Enter your choice : ");
		if(scanf("%d",&i) <=0)
		{
			printf("Enter only an Integer\n");
			exit(EXIT_FAILURE);
		}
		else
		{
			switch(i)	
			{
				case 1:	
					for(i = 1; i < 10; i++)
					{
						append(i);
					}
					break;

				case 2:	
					printf("Enter the number to add: \n");
					if(scanf("%d",&number) <=0)
					{
						printf("Enter only an Integer\n");
						exit(EXIT_FAILURE);
					}
					else
					{
						add(number);	
					}
					break;

				case 3:	
					printf("Enter the number to append: \n");
					if(scanf("%d",&number) <=0)
					{
						printf("Enter only an Integer\n");
						exit(EXIT_FAILURE);
					}
					else
					{
						append(number);	
					}
					break;

				case 4:	
					printf("Enter the number to insert: \n");
					if(scanf("%d",&number) <=0)
					{
						printf("Enter only an Integer\n");
						exit(EXIT_FAILURE);
					}
					else
					{
						printf("Enter the position: \n");
						if(scanf("%d",&position) <=0)
						{
							printf("Enter only an Integer\n");
							exit(EXIT_FAILURE);
						}
						else
						{
							insert_at(number, position);
						}

					}
					break;

				case 5:
					display();
					break;

				case 6:
					number = count_sum();
					printf("Sum of linked list is %d", number);
					break;

				case 7:

					printf("Enter the number to delete: \n");
					if(scanf("%d",&number) <=0)
					{
						printf("Enter only an Integer\n");
						exit(EXIT_FAILURE);
					}
					else
					{
						delete_number(number);	
					}
					break;

				case 8:
					delete_all();
					break;

				case 0:
					exit(1);
					break;

				default:
					printf("Invalid option\n");
			}

		}
	}

	exit(1);	
}