[basics of C language] 17 preliminary study of linked list

One 、 Linked list (linked list)

1.1 Create header file

node —— node

//node.h
#ifndef _NODE_H_
#define _NODE_H_

typedef struct _node{
    
	int value;					// Value of this cell 
	struct _node * next;		// The first address of the next unit 
} Node;

#endif

1.2 Program examples ： Create a linked list

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

typedef struct _list{
    			// Store the head and tail of the linked list 
	Node* head;
	Node* tail;
} List;

void add( Node* head, int number);

int main(){
    
	
	List list;
	list.head = list.tail = NULL;
	
	int number;
	while( (scanf("%d", &number)) != EOF ){
    
		add(&list, number);
	}
	
	return 0;
}

Two 、 Functions of linked lists

// The parameters are the head and tail of the original linked list , And the value to be stored 
void add( List* pList, int number)
{
    
	// Create a new cell 
	Node* p = (Node*)malloc(sizeof(Node));
	p->value = number;
	p->next = NULL;				// The pointer member of the last structural unit is null 
	
	// Judge pList Whether it points to NULL
	if(pList){
    
		pList->tail = p;
	}
	else{
    
		pList->head = p;
	}
}

3、 ... and 、 Search of linked list

3.1 Traversal of the list

// Traversal of the list 
Node *p;
for(p = list.head; p; p = p->next){
    
	printf("%d\t", p->value);
}
printf("\n");

// Linked list traversal function 
void print(List* pList){
    
	Node *p;
	for(p = pList->head; p; p = p->next){
    
		printf("%d\t", p->value);
	}
	printf("\n");
}

3.2 Search for linked list elements

// Search whether there is a certain number in the linked list 
int number, isFound = 0;
scanf("%d", &number);
Node *p;
for( p=list.head; p; p = p->next){
    
	if(p->value == number){
    
		printf(" Call me ！\n");
		isFound = 1;
		break;
	}
}
if(!isFound) printf(" Did not find .\n");


// Function form 
void search(List* pList, int number)
{
    
	int isFound = 0;
	Node *p;
	for( p=pList->head; p; p = p->next){
    
		if(p->value == number){
    
			printf(" Call me ！\n");
			isFound = 1;
			break;
		}
	}
	if(!isFound) printf(" Did not find .\n");
}

Four 、 Deletion of linked list units

// Delete a cell in the linked list 
void delete(List* pList, int number)
{
    
	Node *p, *q;		// Record the unit p, and p Last unit of 
	for(q=NULL, p=pList->head; p; q=p, p=p->next){
    
		// Link two adjacent cells of the target cell ( Skip target unit )
		if(p->value == number){
    
			if( q ){
    
				q->next = p->next;
			}
			else{
    
				pList->head = p->next;
			}
			free(p);		// Free the memory space of the target unit 
			break
		}
	}
}

When using a pointer to a linked list unit , You need to consider whether the pointer is a null pointer .

5、 ... and 、 Clearing the linked list

void flush(List* pList)
{
    
	Node*p, *q;
	for(p=pList->head; p; p=q){
    
		q = p->next;
		free(p);
	}
}