| 1. | Initialize an empty stack and empty result string variable 初始化一个空堆栈,将结果字符串变量置空。 |
| 2. | That ensures that it is never called on an empty stack 添加一个断言,以确保pop永远不会在空堆栈上被调用: |
| 3. | Initialize an empty stack 初始化一个空堆栈 |
| 4. | Property is an empty stack 属性为空堆栈。 |
| 5. | State 0 represents the empty stack , state 1 represents the stack with only one element 状态0表示空堆栈,状态1表示只有一个元素: |
| 6. | Consider what happens when a thread tries to pop from an empty stack 下面我们考虑当一个线程试图调用一个空栈的pop ( )操作时的情况。 |