C언어 - 링크드리스트 linklist(추가,수정,삭제,검색,출력) 예제

#include <stdio.h>
#include <stdlib.h>
 
typedef struct game{
 
    int no;    
    char id[20];
    char pw[20];
    struct game *next;
 
}Game;
 
Game *head = NULL,*tail = NULL;
 
int menu()
{
    int input;
 
    printf("1. user_add\n2. user_modify\n3. user_delete\n4. user_search\n5. user_print\n\ninput: ");
    scanf("%d",&input);
 
    return input;
}
 
void user_add()
{
    Game *new_user = (Game*)malloc(sizeof(Game));
 
    printf("user number : ");
    scanf("%d",&new_user->no);
 
    printf("user id : ");
    scanf("%s",new_user->id);
 
    printf("user pw : ");
    scanf("%s",new_user->pw);
 
    if(head == NULL)
        head = tail = new_user;
    else{        
        tail->next = new_user;
        tail = new_user;    
    }        
}
 
void user_modify()
{
    Game *user_modify = head;
 
    int input;
 
    printf("user modify id:");    
    scanf("%d",&input); 
           
    if(user_modify == NULL)    
    {        
        printf("not found data\n");        
        return;    
    }            
 
    while(user_modify != NULL)    
    {        
        if(user_modify->no == input)        
        {            
            printf("=====user_modify=====\nuser_id: ");  
            scanf("%s",user_modify->id); 
            printf("user_pw: ");            
            scanf("%s",user_modify->pw);            
            printf("=====================\n");        
        }                
        
        user_modify = user_modify->next;
    }
}
 
void user_delete()
{
    
    Game *delete_user = head;
    Game *prev_user = NULL;
    
    int input;
 
    printf("delete user id: ");
    scanf("%d",&input);
   
    while(delete_user != NULL)    
    {
        if(delete_user->no == input)        
        {            
            if(head == delete_user)            
            {                
                if(head->next==NULL)                    
                    head=tail=NULL;                
                else                    
                    head = head->next;  
                              
            }else if(tail == delete_user)            
            {                
                prev_user->next = NULL;                
                tail = prev_user;            
            }else
            {                
                prev_user->next = delete_user->next;                            
            }    
                    
            free(delete_user);            
            break;                                           
        }                
    
        prev_user = delete_user;        
        delete_user = delete_user->next;    
    } 
}
 
void user_search()
{    
    Game *user_search = head; 
   
    int input;        
 
    printf("find user id: ");    
    scanf("%d",&input);        
    
    if(user_search == NULL)    
    {        
        printf("not found data\n\n\n");        
        return;    
    }        
    
    while(user_search != NULL)    
    {        
        if(user_search->no == input)        
        {            
            printf("==================\nID: %s\nPW: %s\n==================\n",user_search->id,user_search->pw); 
        }                        
 
        user_search = user_search->next;                
    }
}
 
void user_print()
{    
    Game *user_print = head;        
    
    if(user_print == NULL)    
    {        
        printf("not found data\n\n\n");        
        return;    
    }        
 
    while(user_print != NULL)    
    {        
        printf("==================user_data==================\nno: %d / user_id: %s / user_pw: %s \n",user_print->no,user_print->id,user_print->pw);                        
        user_print = user_print->next;    
    }        
 
    printf("=============================================\n");
}
 
int main(int argc,char *argv[])
{    
    int select;            
 
    while(1)    
    {        
        printf("\n\n");        
 
        select = menu();            
 
        switch(select)        
        {            
            case 1:                
                user_add();                
                break;            
            case 2:                
                user_modify();                
                break;            
            case 3:                
                user_delete();                
                break;            
            case 4:                
                user_search();                
                break;            
            case 5:                
                user_print();                
                break;        
        }    
    }
 
    return 0;
}