链栈问题

[wlnxxn]

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define Stack_ElemType int
typedef struct StackNode {
struct StackNode* next;
Stack_ElemType data;
}StackNode,*LinkStack;
//链栈初始化 // 返回的是链栈的首地址
StackNode* initStack(LinkStack S) {
S = (LinkStack)malloc(sizeof(StackNode));
if (S == NULL) {
printf("内存分配不成功！\n");
return 0;
};
S->next = NULL;
return S;
};
//创建链栈
StackNode* CreatStack(LinkStack S) {
StackNode* p;
int j = 1;
Stack_ElemType t = 0;
while (j) {
printf("请输入栈顶元素,输入-1时结束创建\n ");
scanf_s("%d", &t);
if (t == -1) {
break;
}
p = (LinkStack)malloc(sizeof(StackNode));
if (p == NULL) { // 动态分配空间后要进行判断否则会有警告
printf("内存分配不成功！\n");
return 0;
};
p->data = t;
p->next = S;
S = p;
};

return S;
}
// 链栈的压栈
void pushStack(LinkStack &S, Stack_ElemType e) {
StackNode* p;
p = (LinkStack)malloc(sizeof(StackNode));
if (p == NULL) { // 动态分配空间后要进行判断否则会有警告
printf("内存分配不成功！\n");
return;
}
p->data = e;
p->next = S;
printf("%d\n", p->data);
S = p;// 现在栈顶为刚压栈的p的结点

};
StackNode* popStack(LinkStack S, Stack_ElemType* e) {
StackNode *p;
if (S == NULL) {
return 0;
}
*e = S->data;
p = S;
S = S->next;
free(p);
return S;
};
Stack_ElemType StackLenth(StackNode S) {
int i = 1;
StackNode* p;
p = S.next;
while (p) {
p = p->next;
i++;
};
return i;
}
int main(void) {
StackNode* S;
S = NULL;
Stack_ElemType j = 0;
S = initStack(S);

S = CreatStack(S);

for (int i = 0; i < 5; i++) {
S = popStack(S, &j);
printf("%d\n", j);
};
S = popStack(S, &j);
printf("%d\n", j);
return 0;
}





请问一下 我加红的字体 为什么在这个函数内更改了S 的 地址 返回函数的时候却是已经被释放的p的地址呢？
但是我又返回了S的地址才可以继续下去

[自信男孩]

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

//#define Stack_ElemType int
typedef  int Stack_ElemType;// int
typedef struct StackNode {
    struct StackNode* next;
    Stack_ElemType data;
}StackNode,*LinkStack;

//链栈初始化 // 返回的是链栈的首地址
//StackNode* initStack(LinkStack S) {
StackNode* initStack(LinkStack *S)
{
    *S = (LinkStack)malloc(sizeof(StackNode));
    if (*S == NULL) {
        printf("内存分配不成功！\n");
        return 0;
    }//;
    (*S)->next = NULL;
    return *S;
} //;
//创建链栈
StackNode* CreatStack(LinkStack S)
{
    StackNode* p;
    int j = 1;
    Stack_ElemType t = 0;
    while (j) {
        printf("请输入栈顶元素,输入-1时结束创建\n ");
        //scanf_s("%d", &t);
        scanf("%d", &t);
        if (t == -1) {
            break;
        }
        p = (LinkStack)malloc(sizeof(StackNode));
        if (p == NULL) {  // 动态分配空间后要进行判断否则会有警告
            printf("内存分配不成功！\n");
            //return 0;
            return S;
        }//;
        p->data = t;
        p->next = S;
        S = p;
    }//;

    return S;
}
// 链栈的压栈
void pushStack(LinkStack &S, Stack_ElemType e) {
    StackNode* p;
    p = (LinkStack)malloc(sizeof(StackNode));
    if (p == NULL) {  // 动态分配空间后要进行判断否则会有警告
        printf("内存分配不成功！\n");
        return;
    }
    p->data = e;
    p->next = S;
    printf("%d\n", p->data);
    S = p;// 现在栈顶为刚压栈的p的结点

};
StackNode* popStack(LinkStack S, Stack_ElemType* e) {
    StackNode *p;
    if (S == NULL) {
        //return 0;
        return NULL;
    }
    *e = S->data;
    p = S;
    S = S->next;
    free(p);
    return S;
}//;

Stack_ElemType StackLenth(StackNode S) {
    int i = 1;
    StackNode* p;
    p = S.next;
    while (p) {
        p = p->next;
        i++;
    }//;
    return i;
}

int main(void) {
    StackNode* S;
    S = NULL;
    Stack_ElemType j = 0;
    S = initStack(&S);
    S = CreatStack(S);

    //for (int i = 0; i < 5; i++) {
    for (int i = 0; S; i++) {
        S = popStack(S, &j);
        if (S)
            printf("%d\n", j);
    }//;
    S = popStack(S, &j);
    if (S)
        printf("%d\n", j);
    return 0;
}

供参考～

多处出现了多余的分号;其他问题，供参考～

[浪客]

p = S; free(p); 不就是free(S)了么

[源代码大师]

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