Question

typedef struct _node{
  int count;
  char * command;
  struct _node * next;
}Node;

typedef struct _list{
  Node * head;
  Node * cur;
  Node * tail;
}List;

List * history;

void list_init()
{
  history = (List*)malloc(sizeof(history));
  history->head = history->cur = history->tail = NULL;
}

char * copy_command(char * command, int len)
{
   char * temp_command = (char*)malloc(sizeof(char)*(len+1));
   strncpy(temp_command, command, len+1);
   return temp_command;
}

void insert_history(int cnt, char * command)
{
  Node * temp = (Node*)malloc(sizeof(Node));
  temp->count = cnt;
  temp->command = command;
  temp->next = NULL;

  if(history->head == NULL){
    printf("hello %s\n", command);
    history->head = temp;
    printf("hello2 %s\n", temp->command);
  }
  else
    history->cur->next = temp;

  printf("head hello %s\n", history->head->command);
  history->cur = temp;
  history->tail = temp;
}


void print_history()
{
  history->cur = history->head;
  printf("history head: %s   | ", history->head->command);

  while(history->cur != NULL){
    printf("%-3d %s\n", history->cur->count, history->cur->command);
    history->cur = history->cur->next;
  }

  history->cur = history->tail;
}

大家好。当我打电话给这个时，

char str[30] = "history";
list_init();
cur_command = copy_command(str, strlen(str))
insert_history(1, cur_command);
print_history();

我得到了

你好历史
      hello2历史
      你好历史记       历史负责人：�＆amp; @��| 1�＆amp; @��

history是一个全局值，包含指向节点的指针我在insert_history（）函数中打印history-＆gt; head-＆gt;命令时没关系，
但是当我在print_history（）函数中打印history-＆gt; head-＆gt;命令时，它不行当我拨打上面的代码两次时，它按照我的预期工作但是当我第一次打电话时它不起作用。我不知道该怎么做。

虚拟价值在C中出现

0 个答案: