链接列表删除节点后根

Question

我在链接列表中练习，我遇到了一个问题。链表是尾巴，所以我想删除位于根节点上方的第一个元素。我不要在任何情况下想删除根节点。该代码是：

struct goods{ 
    char* section; 
    char* pname; 
    int value; 
    int customer_num; 
    int cash; 
    struct goods* next; 
}; 
void delete_goods(int customer_num,struct goods* root) 
{ 
struct goods *current=root; 
struct goods *previous=NULL; 
while(current!=NULL){ 
    if(current->customer_num == customer_num){ 
    if (previous==NULL){ 
     current=current->next; 
     free(root); 
    } 
    else { 
     previous->next=current->next; 
     free(current); 
     current=previous->next; 
    } 
    } 
    else{ 
    previous=current; 
    current=current->next; 
    } 
} 
} 
int main(){ 
    root = malloc(sizeof(struct goods)); 
    root ->next=NULL; 
    printf("give the number of starting customers\n"); 
    scanf("%d",&customers); 
    inform_list(customers);// adds element to list 



     else if(r=='r'&&customers!=0){ 
      printf("removing...\n"); 
      delete_goods(customers,root); 
      customers-=1; 
      printf("customers:\t%d\n",customers); 
      print(); 
     } 
     } 

我没有张贴整个代码（它包括一些功能添加元素，为您提供方便，如果你喜欢，我可以做链接列表，我需要的方式来解决我的删除功能所以我满足上述需求 下面列表中的一个示例输出：
customers: 2 customer: 2 item value: 32 product name: asdasd customer: 1 item value: 43 product name: sdsad customer: 0 item value: 0 product name: (null) 我需要的是我的删除功能删除客户1，如果问那么顾客2等

Answer 1

正如其他人所说，你要保留根节点，所以你想从root->next开始（即root将始终为非空）。

这应该工作[请原谅无偿风格清理]：

void 
delete_goods(int customer_num, struct goods *root) 
{ 
    struct goods *current = root->next; 
    struct goods *previous = NULL; 
    struct goods *next; 

    for (; current != NULL; current = next) { 
     next = current->next; 

     if (current->customer_num == customer_num) { 
      if (previous != NULL) 
       previous->next = next; 
      else 
       root->next = next; 

      free(current); 
     } 
     else 
      previous = current; 
    } 
} 

这里有一个稍微更紧凑的版本：

void 
delete_goods(int customer_num, struct goods *root) 
{ 
    struct goods *current = root->next; 
    struct goods *previous = root; 
    struct goods *next; 

    for (; current != NULL; current = next) { 
     next = current->next; 

     if (current->customer_num == customer_num) { 
      previous->next = next; 
      free(current); 
     } 
     else 
      previous = current; 
    } 
}