链栈的基本操作

/**
 * @author:
 * @version:1.0
 */
#include "bits/stdc++.h"

using namespace std;

#define OK 0
#define ERROR -1

typedef struct StackNode {
    int elem;
    struct StackNode *next;
} StackNode, *LinkStack;

int InitStack(LinkStack &S) {
    //构造一个空栈
    S = NULL;
    cout << "链栈已经初始化" << endl;
    return OK;
}

int StackEmpty(LinkStack S) {
    //判断栈空
    if (S == NULL) {
        cout << "链栈为空" << endl;
    } else {
        cout << "链栈不为空" << endl;
    }
    return OK;
}

int Push(LinkStack &S, int e) {
    //入栈
    LinkStack p = new StackNode;
    if (p == NULL) {
        cerr << "结点创建失败" << endl;
        return ERROR;
    }
    p->elem = e;//将新的节点的数据域设置为e
    p->next = S;//将新节点插入栈顶
    S = p;//修改栈顶指针
    cout << "入栈成功" << endl;
    return OK;
}

int Pop(LinkStack &S) {
    //弹栈
    if (S == NULL) {
        cerr << "弹栈失败" << endl;
        return ERROR;
    }
    LinkStack p = S;
    S = S->next;
    delete p;
    cout << "弹栈成功" << endl;
    return OK;
}

int GetTop(LinkStack S) {
    //取栈顶
    if (S != NULL) {
        return S->elem;
    }
}

int main() {
    LinkStack S;
    InitStack(S);
    int choice;
    do {
        cout << "*****************" << endl;
        cout << "1.入栈" << endl;
        cout << "2.出栈" << endl;
        cout << "3.判断栈空" << endl;
        cout << "4.取栈顶" << endl;
        cout << "*****************" << endl;
        cout << "请输入您的操作:" << endl;
        cin >> choice;
        switch (choice) {
            case 1: {
                int e;
                cout << "请输入您要入栈的元素:" << endl;
                cin >> e;
                Push(S, e);
                break;
            }
            case 2: {
                Pop(S);
                break;
            }
            case 3: {
                StackEmpty(S);
                break;
            }
            case 4: {
                int res = GetTop(S);
                cout << "栈顶元素为:" << res << endl;
                break;
            }
            default: {
                exit(ERROR);
            }
        }
    } while (1);
    return 0;
}