和中缀转换后缀的算法相反，那是把操作符存储在栈里。

This is the opposite of the infix to postfix translation algorithm, where operators were stored on the stack.

youdao

当它是一个操作符时，从栈中弹出两个数进行运算，并且将运算结果压入栈中。

When it is an operator, pop two Numbers from the stack, do the calculation, and push back the result.

youdao