stackLinkedList

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

struct Stack
{
  int data;
  struct Stack *next;
} * Top = NULL;

void push(int x)
{
  struct Stack *t = (struct Stack *) malloc(sizeof(Struct Stack));
  if (!t ) return;
  t->data = x;
  t->next = Top;
  Top = t;
}
int pop() 
{
  x = -1;
  struct Stack *t;
  if ( !isEmpty(st) ) {
    t = Top;
    Top = Top->next;
    x = t->data;
    free(t);
  }
  return x;
}
int peak(int pos) 
{
  struct Stack *t;
  t = Top;
  for ( int i = 0; i < pos-1 && t; i++) {
    t = t->next;
  }
  if ( t ) {
    return t->data;
  } else {
    return -1;
  }
}
class Node
{
public:
  int data;
  Node *next;
}
using namespace std;
class Stack
{
private:
  Node * top;
public:
  Stack() { top = NULL; }
  ~Stack() {};
  void push(int x);
  int pop();
  void Display();
}

void Stack::push(int x)
{
  Node * t = nex Stack();
  if ( !t ) {
    cout << "Stack is full"
  } else {
    t->data = x;
    t->next = top;
    top = t;
  }
}
int Stack::pop()
{
  Node *t;
  int x = -1;
  if (!top) {
    cout << "Stack is empty\n";
  } else {
    t = top;
    top = top->next;
    x = t->data;
    delete t;
  }
  return x;
}
void Stack::Display()
{
  Node *t = top;
  while(t) {
    cout << t->data << " ";
    t = t->next;
  }
  cout << endl;
}

char * convert(char *infix)
{
  char *post = (char *) malloc(sizeof(char) * (strlen(infix) + 1));
  Stack stk;
  int i = 0; j = 0;
  while (infix[i] != '\0') {
    if(isOperand(infix[i]) ) {
      post[j++] = infix[i++];
    } else {
      if ( stk.isEmpty() || preference(infix[i]) > preference(stk.top()) {
        stk.push(infix[i++]);
      } else {
        post[j++] = stk.pop();
      }
    }
  }
  while( !stk.isEmpty()){
    post[j++] = stk.pop();
  }
  post[j] = '\0';
  return post;
}

int Eval(char * post)
{
  Stack<int> stk;
  int val = 0;
  int i = 0;
  int right, left, res;
  while (post[i] != '\0') {
    if ( isOperand(post[i]) ) {
      stk.push(post[i++]-'0');
    } else {
      right = stk.pop();
      left = stk.pop();
      switch(post[i]) {
        case '+':
          res = left + right;
          break;
        case '-' :
          res = left - right;
          break;
        case '*':
          res = left * right;
          break;
        case '/':
          res = left / right;
          break;
        default:
          break;
      }
      stk.push(res);
      i++;
    }
  } 
  return stk.top();
 } 
    
int main()
{
  Stack stk;
  stk.push(1);
  stk.push(2);
  stk.pop();
  stk.pop();
  stk.Display();
  return 1;
}