栈(stack)--c实现(使用双链表)

是不是直接贴代码不太好，我竟然不知道说什么。

写这个考虑的问题，或者是纠结的问题是这个头指针怎么处理，也就是栈的顶部，最后采用的是初始化第一个栈空间浪费掉，栈顶是有元素的。好像应该去学习下画图，没图不太好说。

写数据结构栈的时候发现自己的2个地方需要进一步补习，用的时候心中没谱---指针和内存分配，看来我还是太水，代码里有3个warning没改出来。

 #include <stdio.h>

 typedef struct node
 {
     int data;
     struct node* next;
     struct node* pre;
 }Node;

 //Stack 一直指向栈顶
 typedef Node* Stack;

 void InitStack(Stack* stack);
 void DeleteStack(Stack* stack);
 int TopStack(Stack*);
 void PushStack(Stack* stack, int elem);
 int PopStack(Stack *stack);
 int IsNull(Stack*);
 void PrintStack(Stack *);

 void PrintStack(Stack *stack)
 {
     Node* preNode = *stack;
     while((preNode->pre != NULL)
           &&preNode)
     {
         printf("%d", preNode->data);
         preNode = preNode->pre;
         if(preNode->pre != NULL){
             printf("<==");
         }
     }
     printf("\n");

 }
 //1 means NULL
 //stack-->node-->datamem
 //这个地方第一次写传的是Stack stack，为什么报错？因为穿的是值，就是一个copy，pre不能确定一定是NULL
 int IsNull(Stack *stack)
 {
      return ((*stack)->pre == NULL);
 }

 int PopStack(Stack *stack)
 {
     if(IsNull(stack))
     {
         printf("empty stack.\n");
         return -;
     }
     int popData = -;
     popData = (*stack)->data;
     Node* popNode = NULL ;
     popNode = *stack;
     *stack = (*stack)->pre;
     (*stack)->pre = popNode->pre->pre;
     (*stack)->next = NULL;

     popNode->pre->pre->next = (*stack);

     free(popNode);//warning

     return popData;
 }
 void InitStack(Stack* stack)
 {
     (*stack)->next = NULL;
     (*stack)->pre = NULL;
     (*stack)->data = -;
     return ;
 }

 int TopStack(Stack *stack)
 {
     return (*stack)->data;
 }

 void PushStack(Stack *stack, int elem)
 {
     //Node *pushNode = (Node*)malloc(sizeof(Node));
     Node *pushNode = (Node*) malloc(sizeof(Node));//warning
     if(pushNode == NULL)
      {
          printf("malloc error at line %d.", __LINE__);
          return;
      }

     pushNode->data = elem;
     pushNode->next = NULL;
     pushNode->pre = *stack;
     (*stack)->next = pushNode;
     *stack = (*stack)->next;

 }

 void DeleteStack(Stack* stack)
 {

     Node* preNode = stack;
     while((*stack)->pre != NULL)
     {
         PopStack(stack);

     }
     free(*stack);

     return ;
 }

 int main(void)
 {
     printf("Hello World!\n");
     Stack *stack =NULL;
     stack = (Stack*)malloc(sizeof(stack));//warning
     *stack = (Node*)malloc(sizeof(Node));
     InitStack(stack);
     IsNull(stack);
     printf("isNull=[%d]\n", IsNull(stack));
     printf("the top ele is [%d]\n", (*stack)->data);
     printf("push elem  1, 2, 3, 4, 3\n");
     PushStack(stack, );
     PrintStack(stack);
     PushStack(stack, );
     PushStack(stack, );
     PushStack(stack, );
     PushStack(stack, );
     printf("print the curr stack.\n");
     PrintStack(stack);
     printf("Pop the stack and print the curr stack.\n");
     PopStack(stack);
     PrintStack(stack);

     printf("the top elem is %d\n", TopStack(stack));

     return ;
 }

是不是也把运行结果贴上去？？

QT运行的，懒得去开虚拟机在linux跑，太费事，还要改MAKEFILE.

运行结果：/*******************begin

Hello World!
isNull=[1]
the top ele is [-1]
push elem  1, 2, 3, 4, 3
1
print the curr stack.
3<==4<==3<==2<==1
Pop the stack and print the curr stack.
4<==3<==2<==1
the top elem is 4

************end*******/

下一篇写队列吧，想了下定义头尾指针好像会好用点。