怎么说是取消对空指针s的引用呢

Question

#include using namespace std;typedef struct StackNode{ int date; struct StackNode* next;}StackNode,*LinkStack;void Init(LinkStack& S){//构造一个空栈，栈顶指针置空 S->next= NULL;}void Push(LinkStack& S, int e){ LinkStack p = new StackNode;//生成新结点 p->date = e; p->next = S; S = p;}int Pop(LinkStack& S){ if (S = NULL) return 0; LinkStack q = S; S = S->next; delete q; return true;}void GetTop(LinkStack& S){ cout << S->date << endl;}int main(){ LinkStack S; Init(S); int n; cout << "要存入链栈的元素个数n：" << endl; cin >> n; cout << "要输入元素的值：" << endl; for (int i = 0; i < n; i++) { int e; cin >> e; Push(S, e); } Pop(S); GetTop(S); return true;}

Answer 1

你主函数的S都没分配内存怎么就用