c - 如何在C中更新全局链表？

Question

我有一个名为 ACCOUNT 的结构，它有两个属性和一个指向下一个属性的指针。全局头由 NULL 启动。我想更新全局列表，但当我多次调用该函数时，头部仍然为 NULL。如何解决？

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

     struct ACCOUNT{
                   int accountNumber;
                   float balance;
                    struct ACCOUNT *next;
} 
      struct ACCOUNT *head = NULL ;


     void findUpdate(int account, float amount){

        struct ACCOUNT *current;
        current = head;
        while(current!=NULL){
                if (current->accountNumber==account){
                        current->balance += amount;
                }
        current=current->next;
        }
         current = (struct ACCOUNT*) malloc(sizeof(struct ACCOUNT));
        current->accountNumber = account;
        current->balance = amount;
}

Answer 1

您需要将 findUpdate 末尾分配的新条目链接到列表中。我建议将 findUpdate 重写为:

void findUpdate(int account, float amount)
  {
  struct ACCOUNT *current;

  for(current = head ; current != NULL ; current = current->next)
    {
    if(current->accountNumber == account)
      {
      current->balance += amount;
      break;
      }
    }

  if(current == NULL)
    {
    current = malloc(sizeof(struct ACCOUNT));
    current->accountNumber = account;
    current->balance = amount;
    current->next = head;
    head = current;
    }
  }