/*

对栈实现初始化，插入栈顶元素，删除栈顶元素，遍历栈，清空栈等基本操作

*/

1 #include 
        
            2 #include 
         
             3 #include 
          
              4   5 #define true 1   6 #define false 0   7   8   9 typedef struct Node  10 {
        11     int data;  12     struct Node *pNext;  13 }NODE, *PNODE;  14  15 typedef struct Stack  16 {
        17     PNODE pTop;  18     PNODE pBottom;  19 }STACK, *PSTACK;  20  21 void init(PSTACK pS);  22 void push(PSTACK pS, int val);  23 void traverse(PSTACK pS);  24 int pop(PSTACK pS , int *val);  25 void clear(PSTACK pS);  26 int empty(PSTACK pS);  27  28 int main(void)  29 {
        30     STACK S ;  31     int val;  32     int i;  33      34     init(&S);  35      36     push(&S,1);  37     push(&S,2);  38     push(&S,3);  39     push(&S,4);  40     push(&S,5);  41     push(&S,6);  42  43     traverse(&S);  44      45     if(pop(&S ,&val))  46     {
        47         printf("遍历成功，出栈元素为%d\n",val);  48     }  49     else  50     {
        51         printf("出栈失败！\n");  52     }  53     traverse(&S);  54  55     clear(&S);  56      57     traverse(&S);  58      59     return 0 ;  60 }  61  62 //栈的初始化  63 void init(PSTACK pS)  64 {
        65     pS -> pTop = (PNODE)malloc(sizeof(NODE));  66      67     if(NULL == pS -> pTop)  68     {
        69         printf("动态内存分配失败！");  70         exit(-1);  71     }  72     else  73     {
        74         pS -> pBottom = pS -> pTop;  75         pS -> pTop -> pNext = NULL;  76     }  77      78     return ;  79 }  80  81 //插入元素到栈顶  82 void push(PSTACK pS , int val)  83 {
        84     PNODE pNew = (PNODE)malloc(sizeof(NODE));  85      86     pNew -> data = val;  87     pNew -> pNext = pS -> pTop;  88     pS -> pTop = pNew;  89      90     return ;  91 }  92  93 //遍历栈S  94 void traverse(PSTACK pS)  95 {
        96     PNODE p = pS -> pTop;  97      98     printf("栈内元素为：");  99     while(p != pS -> pBottom) 100     {
       101         printf("%d\t", p -> data); 102         p = p -> pNext; 103     } 104     105     printf("\n"); 106     return ; 107 } 108 109 //判断栈是否为空 110 int empty(PSTACK pS) 111 {
       112     if(pS -> pTop == pS -> pBottom) 113     {
       114         return true; 115     } 116     else 117         return false; 118 } 119 120 //删除栈顶元素并将其值赋给*val 121 int pop(PSTACK pS , int *val) 122 {
       123     if(empty(pS)) 124     {
       125         return false; 126     } 127     else 128     {
       129         PNODE r = pS -> pTop; 130         *val = r -> data; 131         pS -> pTop = r -> pNext; 132         free(r); 133         r = NULL; 134     } 135 } 136 137 //清空栈S 138 void clear(PSTACK pS) 139 {
       140     if(empty(pS)) 141     {
       142         return; 143     } 144     else 145     {
       146         PNODE p = pS -> pTop; 147         PNODE q = NULL; 148         149         while(p != pS -> pBottom) 150         {
       151             q = p -> pNext; 152             free(p); 153             p = q ; 154         } 155         156         pS -> pTop = pS -> pBottom; 157         158         return; 159     } 160 }