title: C check if array stack its empty or not problem
body: <p>I create array stack and 2 fuctions. Fuction push to add something to the stack and fuction isempty to check if the stack are empty but its not work, so where is the mistake.</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;conio.h&gt;
  #include &lt;stdlib.h&gt;
  
  #define MAX 10
  
  struct stack
  {
      int items[MAX];
      int top;
  };
  
  typedef struct stack st;
  
  int isempty(st *s)
  {
      if (s-&gt;top==-1)
      {
          printf("it's empty");
      }
      else
      {
          printf("it's not empty");
      }
  }
  
  void push(st *s)
  {
      int newitem;
      printf("Enter item: ");
      scanf("%d",&amp;newitem);
      s-&gt;top++;
      s-&gt;items[s-&gt;top]=newitem;
  }
  
  int main()
  {
      st *s;
      push(s);
      isempty(s);
      return 0;
  }
  </code></pre>