以字符序列的方式从终端输入语法正确的，不含变量的整数表达式。利用中缀表达式变为后缀表达式的求值算法实现对算术四则混合运算表达式求值，并演示出在求值中运算符栈，操作数栈，输入字符和主要操作的变化过程。-The way to sequence of characters from the terminal input grammar correctly, do not contain variables integer expression. Use midfix expression of the evaluated a suffix expression of arithmetic algorithm to realize four mixed operation expressions are evaluated, and play in the evaluated operators stack, operand stack, input character and the changing process of the main operation.