共享栈结构体定义和操作

#include<iostream>
using namespace std;
#define maxsize 100
#define elemtp int 
typedef struct {
  elemtp stack[maxsize];
  int top[2];
}stk;
stk s;
int push(int i, elemtp x) {
  if (i < 0 || i>1) {
    cout << "栈号输入不对" << endl;
    exit(0);
  }
  if (s.top[1] - s.top[2] == 1) {
    cout << "栈已满" << endl;
    return 0;
  }
  switch (i)
  {
    case 0:s.stack[++s.top[0]] = x; return 1; break;
    case 1:s.stack[--s.top[1]] = x; return 1;
  }
}
elemtp pop(int i) {
  if (i < 0 || i>1) {
    cout << "栈号输入不对" << endl;
    exit(0);
  }
  switch (i) {
  case 0:
    if (s.top[0] == 1) {
      cout << "栈空" << endl;
      return -1;
    }
  }
}
int main() {
  while (1) {
    cout << "请选择操作：1.入栈  2.出栈" << endl;
    int opt=0;
    cin >> opt;
    switch (opt)
    {
    case 1:{
      cout << "请输左栈，还是右栈" << endl;
      int top = 0;
      cin >> top;
      cout << "入栈数字" << endl;
      int num = 0;
      cin >> num;
      push(top, num);
      break;
    }
    case 2:{
      cout << "请输左栈，还是右栈" << endl;
      int top = 0;
      cin >> top;
      pop(top);
      break;
    }
    }
  }
}