实现计算器的基本功能。中间包含了多种报错的功能（除零、括号的匹配等），实现计算器的加减乘除、括号、浮点数、负数的计算等。-To achieve the basic function calculator. The middle contains a variety of Baocuo functions (except for zero, bracket matching, etc.) to achieve the addition and subtraction multiplication