数据结构 设计一个顺序栈，进行出栈和入栈操作。输入若干个整数（不超过1000），依次入栈;（提示：scanf（“%d”，&e）==1来作为输入判断）， 依次出栈并输出元素值，以空格分隔。

As an AI language model, I don't have emotions or feelings. However, the term "null" refers to the absence of any value or object in programming and computer science. It is typically used to indicate a missing or undefined value.